CCNP BCMSN Portable Command Guide 1587201887, 9781587201882

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CCNP BCMSN Portable Command Guide Scott Empson

Cisco Press 800 East 96th Street Indianapolis, IN 46240 USA

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CCNP BCMSN Portable Command Guide Scott Empson Copyright © 2007 Cisco Systems, Inc. Published by: Cisco Press 800 East 96th Street Indianapolis, IN 46240 USA All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission from the publisher, except for the inclusion of brief quotations in a review. ISBN-10: 1-58720-188-7 ISBN-13: 978-1-58720-188-2 Printed in the United States of America 1 2 3 4 5 6 7 8 9 0 First Printing June 2007 Library of Congress Cataloging-in-Publication Data Empson, Scott. CCNP BCMSN portable command guide / Scott Empson. p. cm. ISBN 978-1-58720-188-2 (pbk.) 1. Computer networks--Problems, exercises, etc. 2. Computer networks--Examinations-Study guides. 3. Packet switching (Data transmission)--Examinations--Study guides. I. Title. TK5105.8.C57E57 2007 004.6'6--dc22 2007019367

Warning and Disclaimer This book is designed to provide information about the Certified Cisco Networking Professional (CCNP) 642-812 Building Cisco Multilayer Switched Networks (BCMSN) exam and the commands needed at this level of network administration. Every effort has been made to make this book as complete and as accurate as possible, but no warranty or fitness is implied. The information is provided on an “as is” basis. The author, Cisco Press, and Cisco Systems, Inc. shall have neither liability nor responsibility to any person or entity with respect to any loss or damages arising from the information contained in this book or from the use of the discs or programs that may accompany it. The opinions expressed in this book belong to the author and are not necessarily those of Cisco Systems, Inc.

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Trademark Acknowledgments All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized. Cisco Press or Cisco Systems, Inc. cannot attest to the accuracy of this information. Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark.

Feedback Information At Cisco Press, our goal is to create in-depth technical books of the highest quality and value. Each book is crafted with care and precision, undergoing rigorous development that involves the unique expertise of members from the professional technical community. Readers’ feedback is a natural continuation of this process. If you have any comments regarding how we could improve the quality of this book, or otherwise alter it to better suit your needs, you can contact us through email at [email protected]. Please make sure to include the book title and ISBN in your message. We greatly appreciate your assistance.

Corporate and Government Sales Cisco Press offers excellent discounts on this book when ordered in quantity for bulk purchases or special sales. For more information please contact: U.S. Corporate and Government Sales 1-800-382-3419 [email protected] For sales outside the U.S. please contact: International Sales [email protected] Publisher: Paul Boger Associate Publisher: David Dusthimer Executive Editor: Mary Beth Ray Cisco Representative: Anthony Wolfenden Cisco Press Program Manager: Jeff Brady Managing Editor: Patrick Kanouse Senior Development Editor: Christopher Cleveland Project Editor: Seth Kerney Copy Editor: Keith Cline Proofreader: Water Crest Publishing, Inc. Technical Editors: Tami Day-Orsatti and David Kotfila Team Coordinator: Vanessa Evans Book Designer: Louisa Adair Composition: Mark Shirar

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About the Author Scott Empson is currently the assistant program chair of the bachelor of applied information systems technology degree program at the Northern Alberta Institute of Technology in Edmonton, Alberta, Canada, where he teaches Cisco routing, switching, and network design courses in a variety of different programs—certificate, diploma, and applied degree—at the post-secondary level. Scott is also the program coordinator of the Cisco Networking Academy Program at NAIT, a Regional Academy covering central and northern Alberta. He has earned three undergraduate degrees: a bachelor of arts, with a major in English; a bachelor of education, again with a major in English/language arts; and a bachelor of applied information systems technology, with a major in network management. He currently holds several industry certifications, including CCNP, CCDA, CCAI, and Network+. Before instructing at NAIT, he was a junior/senior high school English/language arts/computer science teacher at different schools throughout northern Alberta. Scott lives in Edmonton, Alberta, with his wife, Trina, and two children, Zachariah and Shaelyn, where he enjoys reading, performing music on the weekend with his classic rock band “Miss Understood,” and studying the martial art of Taekwon-Do.

About the Technical Reviewers Tami Day-Orsatti (CCSI, CCDP, CCNP, CISSP, MCT, MCSE 2000/2003: Security) is an IT networking and security instructor for T2 IT Training. She is responsible for the delivery of authorized Cisco, (ISC)2, and Microsoft classes. She has more than 23 years in the IT industry working with many different types of organizations (private business, city and federal government, and the Department of Defense), providing project management and senior-level network and security technical skills in the design and implementation of complex computing environments. David Kotfila (CCNP, CCAI) is the director of the Cisco Academy at Rensselaer Polytechnic Institute (RPI), Troy, New York. Under his direction, more than 125 students have received their CCNP, and 6 students have obtained their CCIE. David is a consultant for Cisco, working as a member of the CCNP assessment group. His team at RPI is authoring the four new CCNP lab books for the Academy program. David has served on the National Advisory Council for the Academy program for four years. Previously, he was the senior training manager at PSINet, a Tier 1 global Internet service provider. When David is not staring at his beautiful wife, Kate, or talking with his two wonderful children, Chris and Charis, he likes to kayak and lift weights.

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Dedications This book is dedicated to Trina, Zach, and Shae, without whom I couldn’t have made it through those long nights of editing.

Acknowledgments Anyone who has ever has anything to do with the publishing industry knows that it takes many, many people to create a book. It may be my name on the cover, but there is no way that I can take credit for all that occurred to get this book from idea to publication. Therefore, I must thank a number of people. The team at Cisco Press—once again, you amaze me with your professionalism and the ability to make me look good. Mary Beth, Chris, Patrick, and Seth—thank you for your continued support and belief in my little engineering journal. To my technical reviewers, Tami and David—thanks for keeping me on track and making sure that what I wrote was correct and relevant. To the staff of the Cisco office here in Edmonton—thanks for putting up with me and my continued requests to borrow equipment for development and validation of the concepts in this book. To Rick Graziani—thank you for showing me how to present this material to my students in a fun and entertaining way, and in an educational manner. Finally, big thanks go out to Hans Roth. There are not enough superlatives in the dictionary to describe Hans and his dedication to not only education, but also to the world of networking in general. While I was working on this series of books, Hans decided that he needed to leave the Ivory Tower of Education and get his hands dirty again in industry. So what better way to get back into the swing of things than to go to Africa and design and help install a new converged infrastructure for an entire country? He also had enough time to listen to my ideas, make suggestions, and build most of the diagrams that are in this book. His input has always been invaluable, and for that, I thank you.

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Contents at a Glance Introduction

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Chapter 1 Network Design Requirements Chapter 2 VLANs

1

3

Chapter 3 STP and EtherChannel Chapter 4 Inter-VLAN Routing Chapter 5 High Availability

17

43

59

Chapter 6 Wireless Client Access

75

Chapter 7 Minimizing Service Loss and Data Theft Chapter 8 Voice Support in Campus Switches Appendix Create Your Own Journal Here

125

121

101

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Contents Introduction

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Chapter 1 Network Design Requirements 1 Cisco Service-Oriented Network Architecture 1 Cisco Enterprise Composite Network Model 2 Chapter 2 VLANs 3 Creating Static VLANs 3 Using VLAN-Configuration Mode 3 Using VLAN Database Mode 4 Assigning Ports to VLANs 5 Using the range Command 5 Dynamic Trunking Protocol 5 Setting the Encapsulation Type 6 Verifying VLAN Information 7 Saving VLAN Configurations 7 Erasing VLAN Configurations 8 Verifying VLAN Trunking 9 VLAN Trunking Protocol 9 Using Global Configuration Mode 9 Using VLAN Database Mode 10 Verifying VTP 12 Configuration Example: VLANs 13 3560 Switch 13 2960 Switch 15 Chapter 3 STP and EtherChannel 17 Spanning Tree Protocol 18 Enabling Spanning Tree Protocol 18 Configuring the Root Switch 18 Configuring a Secondary Root Switch 19 Configuring Port Priority 19 Configuring the Path Cost 20 Configuring the Switch Priority of a VLAN Configuring STP Timers 21 Verifying STP 21 Optional STP Configurations 22 PortFast 22 BPDU Guard 22 BPDU Filtering 23 UplinkFast 24

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BackboneFast 24 Root Guard 24 Loop Guard 25 Unidirectional Link Detection 25 Changing the Spanning-Tree Mode 26 Extended System ID 27 Enabling Rapid Spanning Tree 27 Enabling Multiple Spanning Tree 28 Verifying MST 29 Troubleshooting Spanning Tree 29 Configuration Example: STP 30 Core Switch (3560) 30 Distribution 1 Switch (3560) 31 Distribution 2 Switch (3560) 32 Access 1 Switch (2960) 33 Access 2 Switch (2960) 34 EtherChannel 34 Interface Modes in EtherChannel 35 Guidelines for Configuring EtherChannel 35 Configuring L2 EtherChannel 36 Configuring L3 EtherChannel 36 Verifying EtherChannel 37 Configuration Example: EtherChannel 38 DLSwitch (3560) 39 ALSwitch1 (2960) 40 ALSwitch2 (2960) 41 Chapter 4 Inter-VLAN Routing 43 Configuring Cisco Express Forwarding 43 Verifying CEF 44 Troubleshooting CEF 44 Inter-VLAN Communication Using an External Router: Router-on-a-Stick 45 Inter-VLAN Communication Tips 46 Inter-VLAN Communication on a Multilayer Switch Through a Switch Virtual Interface 46 Removing L2 Switchport Capability of a Switch Port 46 Configuring Inter-VLAN Communication 47 Configuration Example: Inter-VLAN Communication 48 ISP Router 49 CORP Router 50 L2Switch2 (Catalyst 2960) 52

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L3Switch1 (Catalyst 3560) L2Switch1 (Catalyst 2960)

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Chapter 5 High Availability 59 Hot Standby Routing Protocol 59 Configuring HSRP 59 Verifying HSRP 60 HSRP Optimization Options 60 Preempt 60 HSRP Message Timers 61 Interface Tracking 62 Debugging HSRP 62 Virtual Router Redundancy Protocol 62 Configuring VRRP 63 Verifying VRRP 64 Debugging VRRP 64 Gateway Load Balancing Protocol 65 Configuring GLBP 65 Verifying GLBP 68 Debugging GLBP 68 Configuration Example: HSRP 69 Router 1 69 Router 2 70 Configuration Example: GLBP 71 Router 1 72 Router 2 73 Chapter 6 Wireless Client Access 75 Configuration Example: 4402 WLAN Controller Using the Configuration Wizard 75 Configuration Example: 4402 WLAN Controller Using the Web Interface 84 Configuration Example: Configuring a 3560 Switch to Support WLANs and APs 94 Configuration Example: Configuring a Wireless Client 96 Chapter 7 Minimizing Service Loss and Data Theft 101 Configuring Static MAC Addresses 101 Switch Port Security 102 Verifying Switch Port Security 103 Sticky MAC Addresses 104 Mitigating VLAN Hopping: Best Practices 105

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Configuring Private VLANs 105 Verifying PVLANs 106 Configuring Protected Ports 107 VLAN Access Maps 107 Verifying VLAN Access Maps 109 Configuration Example: VLAN Access Maps 109 DHCP Snooping 111 Verifying DHCP Snooping 113 Dynamic ARP Inspection 113 Verifying DAI 114 802.1x Port-Based Authentication 114 Cisco Discovery Protocol Security Issues 116 Configuring the Secure Shell Protocol 117 vty ACLs 117 Restricting Web Interface Sessions with ACLs 118 Disabling Unneeded Services 118 Securing End-Device Access Ports 119 Chapter 8 Voice Support in Campus Switches 121 Attaching a Cisco IP Phone 121 Verifying Configuration After Attaching a Cisco IP Phone Configuring AutoQoS: 2960/3560 123 Verifying AutoQoS Information: 2960/3560 124 Configuring AutoQoS: 6500 124 Verifying AutoQoS Information: 6500 124 Appendix Create Your Own Journal Here

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Icons Used in This Book

Switch

Access Server

Ethernet Connection

Laptop

IP Phone

Serial Line Connection

Server

Multilayer Switch

Web Server

PIX Firewall

Router

Wireless Router

Network Cloud

PC

Relational Database

Command Syntax Conventions The conventions used to present command syntax in this book are the same conventions used in the IOS Command Reference. The Command Reference describes these conventions as follows: • Boldface indicates commands and keywords that are entered literally as shown. In actual configuration examples and output (not general command syntax), boldface indicates commands that are manually input by the user (such as a show command). • Italics indicate arguments for which you supply actual values. • Vertical bars (|) separate alternative, mutually exclusive elements. • Square brackets [ ] indicate optional elements. • Braces { } indicate a required choice. • Braces within brackets [{ }] indicate a required choice within an optional element.

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Introduction Welcome to BCMSN! In 2006, Cisco Press came to me and told me, albeit very quietly, that there was going to be a major revision of the CCNP certification exams. They then asked whether I would be interested in working on a command guide in the same fashion as my previous books for Cisco Press: the Cisco Networking Academy Program CCNA Command Quick Reference and the CCNA Portable Command Guide. The original idea was to create a single-volume command summary for all four of the new CCNP exams. However, early on in my research, I quickly discovered that there was far too much information in the four exams to create a single volume—that would have resulted in a book that was neither portable nor quick as a reference. So, I jokingly suggested that they let me author four books—one for each exam. Well, I guess you have to be careful what you wish for, because Cisco Press readily agreed. They were so excited about the idea that they offered to cut the proposed writing time by a few months to get these books to market faster. How nice of them, don’t you think? This book is the second in a four-volume set that attempts to summarize the commands and concepts that you need to pass one of the CCNP certification exams—in this case, the Building Cisco Multilayer Switched Networks exam. It follows the format of my previous books, which are in fact a cleaned-up version of my own personal engineering journal. I have long been a fan of what I call the “Engineering Journal”—a small notebook that can be carried around and that contains little nuggets of information—commands that you forget, the IP addressing scheme of some remote part of the network, little reminders about how to do something you only have to do once or twice a year, but is vital to the integrity and maintenance of your network. This journal has been a constant companion by my side for the past eight years; I only teach some of these concepts every second or third year, so I constantly need to refresh commands and concepts, and learn new commands and ideas as they are released by Cisco. With the creation of two brand-new CCNP exams, the amount of new information out there is growing on an almost daily basis. There is always a new white paper to read, a new Webinar to view, another slideshow from a Networkers session that I didn’t get to. My journals are the best way for me to review because they are written in my own words, words that I can understand. At least, I better understand them, because if I didn’t, I have only myself to blame. To make this guide a more realistic one for you to use, the folks at Cisco Press have decided to continue with my request for an appendix of blank pages—pages that are for you to put your own personal touches—your own configurations, commands that are not in this book but are needed in your world, and so on. That way this book will look less like my journal and more like your own. I hope that you learn as much from reading this guide as I did when I wrote it.

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Networking Devices Used in the Preparation of This Book To verify the commands in this book, I had to try them out on a few different devices. The following is a list of the equipment I used in the writing of this book: • C2620 router running Cisco IOS Software Release 12.3(7)T, with a fixed Fast Ethernet interface, a WIC-2A/S serial interface card, and a NM-1E Ethernet interface • C2811 ISR bundle with PVDM2, CMME, a WIC-2T, FXS and FXO VICs, running 12.4(3g) IOS • WS-C3560-24-EMI Catalyst switch, running 12.2(25)SE IOS • WS-C3550-24-EMI Catalyst switch, running 12.1(9)EA1c IOS • WS-C2960-24TT-L Catalyst switch, running 12.2(25)SE IOS • WS-C2950-12 Catalyst switch, running Version C2950-C3.0(5.3)WC(1) Enterprise Edition software • AIR-WLC4402 Wireless LAN Controller These devices were not running the latest and greatest versions of Cisco IOS Software. Some of it is quite old. Those of you familiar with Cisco devices will recognize that a majority of these commands work across the entire range of the Cisco product line. These commands are not limited to the platforms and Cisco IOS versions listed. In fact, in most cases, these devices are adequate for someone to continue his or her studies beyond the CCNP level, too.

Who Should Read This Book This book is for those people preparing for the CCNP BCMSN exam, whether through selfstudy, on-the-job training and practice, study within the Cisco Academy Program, or study through the use of a Cisco Training Partner. There are also some handy hints and tips along the way to make life a bit easier for you in this endeavor. It is small enough that you will find it easy to carry around with you. Big, heavy textbooks might look impressive on your bookshelf in your office, but can you really carry them all around with you when you are working in some server room or equipment closet somewhere?

Organization of This Book This book follows the list of objectives for the CCNP BCMSN exam: • Chapter 1, “Network Design Requirements”—Provides an overview of the two different design models from Cisco—the Service-Oriented Network Architecture and the Enterprise Composite Network Model. • Chapter 2, “VLANs”—Describes how to configure, verify, and troubleshoot VLANs, including topics such as Dynamic Trunking Protocol (DTP) and VLAN Trunking Protocol (VTP).

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• Chapter 3, “STP and EtherChanel”—Describes how to configure, verify, and troubleshoot Spanning Tree Protocol (STP), including topics such as configuring the root switch; port priorities; timers; PortFast; BPDU Guard; UplinkFast and BackboneFast; Configuring L2 and L3 EtherChannel; load balancing; and verifying EtherChannel. • Chapter 4, “Inter-VLAN Routing”—Describes how to configure, verify, and troubleshoot inter-VLAN routing, including topics such as router-on-a-stick; switch virtual interfaces; Cisco Express Forwarding (CEF); and creating a routed port on a switch. • Chapter 5, “High Availability”—Covers topics such as Hot Standby Router Protocol (HSRP), Virtual Router Redundancy Protocol (VRRP), and Gateway Load Balancing Protocol (GLBP). • Chapter 6, “Wireless Client Access”—Describes how to configure and verify the configuration of a wireless LAN controller using both the Command-Line Wizard and the GUI Wizard. • Chapter 7, “Minimizing Service Loss and Data Theft”—Covers topics such as port security, sticky MAC addresses, private VLANs, VLAN access maps, DHCP snooping, dynamic ARP inspection, 802.1x authentication, Cisco Discovery Protocol (CDP) issues, Secure Shell (SSH), vty access control lists (ACL), disabling unneeded services, and securing end device access ports. • Chapter 8, “Voice Support in Campus Switches”—Covers topics such as attaching a Cisco IP Phone, configuring AutoQos on a 2960/3560 switch, configuring AutoQos on a 6500, and verifying AutoQoS information.

Did I Miss Anything? I am always interested to hear how my students, and now readers of my books, do on both vendor exams and future studies. If you would like to contact me and let me know how this book helped you in your certification goals, please do so. Did I miss anything? Let me know. I can’t guarantee I’ll answer your e-mail message, but I can guarantee that I will read all of them. My e-mail address is [email protected].

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CHAPTER 1

Network Design Requirements This chapter provides information concerning the following topics: • Cisco Service-Oriented Network Architecture • Cisco Enterprise Composite Network Model No commands are associated with this module of the CCNP BCMSN course objectives.

Cisco Service-Oriented Network Architecture Figure 1-1 shows the Cisco Service-Oriented Network Architecture (SONA) framework. Cisco SONA Framework

PLM

CRM

ERP

HCM

Procurement

SCM

Collaboration Layer

Application Layer

Figure 1-1

Instant Messaging

Unified Messaging

Meeting Place

IPCC

IP Phone

Video Delivery

Middleware and Application Platforms

Networked Infrastructure Layer

Application-Oriented Networking Voice and Collaboration Services

Security Services Infrastructure Services

Mobility Services

Compute Services Identity Services

Storage Services Network Infrastructure Virtualization Infrastructure Management

Campus

Branch Server

Data Center

Enterprise Edge Storage

Intelligent Information Network

WAN/MAN

Adaptive Management Services

Application Delivery

Services Virtualization

Services Management

Interactive Services Layer

Advanced Analytics and Decision Support

Teleworker

Clients

2

Cisco Enterprise Composite Network Model

Cisco Enterprise Composite Network Model Figure 1-2 shows the Cisco Enterprise Composite Network Model. Figure 1-2

Cisco Enterprise Composite Network Model Enterprise Campus

Enterprise Edge

Building Access

Service Provider Edge

Management E-Commerce

Building Distribution

ISP A Edge Distribution Campus Backbone

Internet Connectivity ISP B

Server Farm

RemoteAccess VPN PSTN

WAN

Frame Relay, ATM, PPP

CHAPTER 2

VLANs This chapter provides information and commands concerning the following topics: • Creating static VLANs — Using VLAN-configuration mode — Using VLAN Database mode • Assigning ports to VLANs • Using the range command • Dynamic Trunking Protocol (DTP) • Setting the encapsulation type • Verifying VLAN information • Saving VLAN configurations • Erasing VLAN configurations • Verifying VLAN trunking • VLAN Trunking Protocol (VTP) — Using VLAN Database mode — Using global configuration mode • Verifying VTP

Creating Static VLANs Static VLANs occur when a switch port is manually assigned by the network administrator to belong to a VLAN. Each port is associated with a specific VLAN. By default, all ports are originally assigned to VLAN 1. There are two different ways to create VLANs: • Using the VLAN-configuration mode, which is the recommended method of creating VLANs • Using the VLAN Database mode (which should not be used, but is still available)

Using VLAN-Configuration Mode vlan 3 Switch(config)#v

Creates VLAN 3 and enters VLANconfig mode for further definitions

name Engineering Switch(config-vlan)#n

Assigns a name to the VLAN. The length of the name can be from 1 to 32 characters.

4

Creating Static VLANs

exit Switch(config-vlan)#e

Applies changes, increases the revision number by 1, and returns to global configuration mode

Switch(config)#

NOTE: This method is the only way to configure extended-range VLANs (VLAN IDs from 1006–4094).

NOTE: Regardless of the method used to create VLANs, the VTP revision number is increased by one each time a VLAN is created or changed.

Using VLAN Database Mode CAUTION: The VLAN Database mode has been deprecated and will be removed in some future Cisco IOS release. It is recommended to use only VLAN-configuration mode.

vlan database Switch#v

Enters VLAN Database mode

vlan 4 name Sales Switch(vlan)#v

Creates VLAN 4 and names it Sales. The length of the name can be from 1 to 32 characters.

vlan 10 Switch(vlan)#v

Creates VLAN 10 and gives it a name of VLAN0010 as a default

apply Switch(vlan)#a

Applies changes to the VLAN database and increases the revision number by 1

exit Switch(vlan)#e

Applies changes to the VLAN database, increases the revision number by 1, and exits VLAN Database mode

Switch#

NOTE: You must apply the changes to the VLAN database for the changes to take effect. You must use either the apply command or the exit command to do so. Using the Ç-z command to exit out of the VLAN database does not work in this mode because it will abort all changes made to the VLAN database—you must either use exit or apply and then the exit command.

Dynamic Trunking Protocol

Assigning Ports to VLANs interface Switch(config)#i fastethernet 0/1

Moves to interface configuration mode

switchport mode Switch(config-if)#s access

Sets the port to access mode

switchport access Switch(config-if)#s vlan 10

Assigns this port to VLAN 10

NOTE: When the switchport mode access command is used, the port will operate as a nontrunking, single VLAN interface that transmits and receives nonencapsulated frames. An access port can belong to only one VLAN.

Using the range Command interface range Switch(config)#i fastethernet 0/1 – 9

Enables you to set the same configuration parameters on multiple ports at the same time NOTE: There is a space before and after the hyphen in the interface range command.

switchport Switch(config-if-range)#s mode access

Sets ports 1–9 as access ports

switchport Switch(config-if-range)#s access vlan 10

Assigns ports 1–9 to VLAN 10

Dynamic Trunking Protocol interface fastethernet Switch(config)#i 0/1

Moves to interface configuration mode

switchport mode Switch(config-if)#s dynamic desirable

Makes the interface actively attempt to convert the link to a trunk link NOTE: With the switchport mode dynamic desirable command set, the interface will become a trunk link if the neighboring interface is set to trunk, desirable, or auto.

5

6

Setting the Encapsulation Type

switchport mode Switch(config-if)#s dynamic auto

Makes the interface able to convert into a trunk link NOTE: With the switchport mode dynamic auto command set, the interface will become a trunk link if the neighboring interface is set to trunk or desirable.

switchport Switch(config-if)#s nonegotiate

Prevents the interface from generating DTP frames. NOTE: Use the switchport mode nonegotiate command only when the interface switchport mode is access or trunk. You must manually configure the neighboring interface to establish a trunk link.

switchport mode Switch(config-if)#s trunk

Puts the interface into permanent trunking mode and negotiates to convert the link into a trunk link NOTE: With the switchport mode trunk command set, the interface becomes a trunk link even if the neighboring interface is not a trunk link.

TIP: The default mode is dependent on the platform. For the 2960 and 3560, the default mode is dynamic auto.

Setting the Encapsulation Type interface 3560Switch(config)#i fastethernet 0/1

Moves to interface config mode

switchport 3560Switch(config-if)#s mode trunk

Puts the interface into permanent trunking mode and negotiates to convert the link into a trunk link

switchport 3560Switch(config-if)#s trunk encapsulation isl

Specifies Inter-Switch Link (ISL) encapsulation on the trunk link

Saving VLAN Configurations

switchport 3560Switch(config-if)#s trunk encapsulation dot1q

Specifies 802.1Q encapsulation on the trunk link

switchport 3560Switch(config-if)#s trunk encapsulation negotiate

Specifies that the interface negotiate with the neighboring interface to become either an ISL or Dot1Q trunk, depending on the capabilities or configuration of the neighboring interface

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TIP: With the switchport trunk encapsulation negotiate command set, the preferred trunking method is ISL.

CAUTION:

The 2960 series switch supports only Dot1Q trunking.

Verifying VLAN Information show vlan Switch#s

Displays VLAN information

show vlan brief Switch#s

Displays VLAN information in brief

show vlan id 2 Switch#s

Displays information of VLAN 2 only

show vlan name marketing Switch#s

Displays information of VLAN named marketing only

show interfaces vlan x Switch#s

Displays interface characteristics for the specified VLAN

Saving VLAN Configurations The configurations of VLANs 1 through 1005 are always saved in the VLAN database. As long as the apply or the exit command is executed in VLAN Database mode, changes are saved. If you are using VLAN-configuration mode, using the exit command will also save the changes to the VLAN database. If the VLAN database configuration is used at startup, and the startup configuration file contains extended-range VLAN configuration, this information is lost when the system boots. If you are using VTP transparent mode, the configurations are also saved in the running configuration, and can be saved to the startup configuration using the copy running-config startup-config command.

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Erasing VLAN Configurations

If the VTP mode is transparent in the startup configuration, and the VLAN database and the VTP domain name from the VLAN database matches that in the startup configuration file, the VLAN database is ignored (cleared), and the VTP and VLAN configurations in the startup configuration file are used. The VLAN database revision number remains unchanged in the VLAN database.

Erasing VLAN Configurations delete flash:vlan.dat Switch#d

Removes entire VLAN database from flash WARNING: Make sure there is no space between the colon (:) and the characters vlan.dat. You can potentially erase the entire contents of the flash with this command if the syntax is not correct. Make sure you read the output from the switch. If you need to cancel, press Ç-c to escape back to privileged mode: (Switch#) Switch#delete flash:vlan.dat Delete filename [vlan.dat]? Delete flash:vlan.dat? [confirm] Switch#

interface Switch(config)#i fastethernet 0/5

Moves to interface config mode

no switchport Switch(config-if)#n access vlan 5

Removes port from VLAN 5 and reassigns it to VLAN 1—the default VLAN

exit Switch(config-if)#e

Moves to global config mode

no vlan 5 Switch(config)#n

Removes VLAN 5 from the VLAN database

or vlan database Switch#v

Enters VLAN Database mode

no vlan 5 Switch(vlan)#n

Removes VLAN 5 from the VLAN database

exit Switch(vlan)#e

Applies changes, increases the revision number by 1, and exits VLAN Database mode

VLAN Trunking Protocol

9

NOTE: When you delete a VLAN from a switch that is in VTP server mode, the VLAN is removed from the VLAN database for all switches in the VTP domain. When you delete a VLAN from a switch that is in VTP transparent mode, the VLAN is deleted only on that specific switch.

NOTE: You cannot delete the default VLANs for the different media types: Ethernet VLAN 1 and FDDI or Token Ring VLANs 1002 to 1005.

CAUTION: When you delete a VLAN, any ports assigned to that VLAN become inactive. They remain associated with the VLAN (and thus inactive) until you assign them to a new VLAN. Therefore, it is recommended that you reassign ports to a new VLAN or the default VLAN before you delete a VLAN from the VLAN database.

Verifying VLAN Trunking show interface fastethernet Switch#s 0/1 switchport

Displays the administrative and operational status of a trunking port

VLAN Trunking Protocol VLAN Trunking Protocol (VTP) is a Cisco proprietary protocol that allows for VLAN configuration (addition, deletion, or renaming of VLANS) to be consistently maintained across a common administrative domain.

Using Global Configuration Mode vtp mode client Switch(config)#v

Changes the switch to VTP client mode

vtp mode server Switch(config)#v

Changes the switch to VTP server mode

vtp mode Switch(config)#v transparent

Changes the switch to VTP transparent mode NOTE: By default, all Catalyst switches are in server mode.

no vtp mode Switch(config)#n

Returns the switch to the default VTP server mode

vtp domain domainSwitch(config)#v name

Configures the VTP domain name. The name can be from 1 to 32 characters long.

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VLAN Trunking Protocol

NOTE: All switches operating in VTP server or client mode must have the same domain name to ensure communication. vtp password Switch(config)#v password

Configures a VTP password. In Cisco IOS Software Release 12.3 and later, the password is an ASCII string from 1 to 32 characters long. If you are using a Cisco IOS release earlier than 12.3, the password length ranges from 8 to 64 characters long. NOTE: To communicate with each other, all switches must have the same VTP password set.

vtp v2-mode Switch(config)#v

Sets the VTP domain to Version 2. This command is for Cisco IOS Software Release 12.3 and later. If you are using a Cisco IOS release earlier than 12.3, the command is vtp version 2. NOTE: VTP Versions 1 and 2 are not interoperable. All switches must use the same version. The biggest difference between Versions 1 and 2 is that Version 2 has support for Token Ring VLANs.

vtp pruning Switch(config)#v

Enables VTP pruning NOTE: By default, VTP pruning is disabled. You need to enable VTP pruning on only one switch in VTP server mode.

NOTE: Only VLANs included in the pruning-eligible list can be pruned. VLANs 2 through 1001 are pruning eligible by default on trunk ports. Reserved VLANs and extended-range VLANs cannot be pruned. To change which eligible VLANs can be pruned, use the interface-specific switchport trunk pruning vlan command: switchport trunk pruning vlan remove 4, 20-30 Switch(config-if)#s ! Removes VLANs 4 and 20-30 switchport trunk pruning vlan except 40-50 Switch(config-if)#s ! All VLANs are added to the pruning list except for 40-50

Using VLAN Database Mode The VLAN Database mode has been deprecated and will be removed in some future Cisco IOS release. Recommended practice dictates using only the VLANconfiguration mode.

VLAN Trunking Protocol

vlan database Switch#v

Enters VLAN Database mode

vtp client Switch(vlan)#v

Changes the switch to VTP client mode

vtp server Switch(vlan)#v

Changes the switch to VTP server mode

vtp transparent Switch(vlan)#v

Changes the switch to VTP transparent mode

11

NOTE: By default, all Catalyst switches are in server mode. vtp domain domainSwitch(vlan)#v name

Configures the VTP domain name. The name can be from 1 to 32 characters long. NOTE: All switches operating in VTP server or client mode must have the same domain name to ensure communication.

vtp password Switch(vlan)#v password

Configures a VTP password. In Cisco IOS Release 12.3 and later, the password is an ASCII string from 1 to 32 characters long. If you are using a Cisco IOS release earlier than IOS 12.3, the password length ranges from 8 to 64 characters long. NOTE: All switches must have the same VTP password set in order to communicate with each other

vtp v2-mode Switch(vlan)#v

Sets the VTP domain to Version 2. This command is for Cisco IOS Release 12.3 and later. If you are using a Cisco IOS release earlier than 12.3, the command is vtp version 2. NOTE: VTP Versions 1 and 2 are not interoperable. All switches must use the same version. The biggest difference between Versions 1 and 2 is that Version 2 has support for Token Ring VLANs.

vtp pruning Switch(vlan)#v

Enables VTP pruning.

12

Verifying VTP

NOTE: By default, VTP pruning is disabled. You need to enable VTP pruning on only one switch in VTP server mode. NOTE: Only VLANs included in the pruning-eligible list can be pruned. VLANs 2 through 1001 are pruning eligible by default on trunk ports. Reserved VLANs and extended-range VLANs cannot be pruned. To change which eligible VLANs can be pruned, use the interface-specific switchport trunk pruning vlan command: Switch(config-if)#switchport trunk pruning vlan remove 4, 20-30 ! Removes VLANs 4 and 20-30 Switch(config-if)#switchport trunk pruning vlan except 40-50 All VLANs are added to the pruning list except for 40 through 50. exit Switch(vlan)#e

Applies changes to VLAN database, increases the revision number by 1, and exits back to privileged mode

Verifying VTP show vtp status Switch#s

Displays general information about VTP configuration

show vtp counters Switch#s

Displays the VTP counters for the switch

NOTE: If trunking has been established before VTP is set up, VTP information is propagated throughout the switch fabric almost immediately. However, because VTP information is advertised only every 300 seconds (5 minutes) unless a change has been made to force an update, it can take several minutes for VTP information to be propagated.

Configuration Example: VLANs

13

Configuration Example: VLANs Figure 2-1 shows the network topology for the configuration that follows, which shows how to configure VLANs using the commands covered in this chapter. Figure 2-1

Network Topology for VLAN Configuration Example VTP Domain BCMSN

10.1.1.0/24

Ports: 1-8 10.1.10.0/24

Administration VLAN 10

Native VLAN 1

10.1.1.0/24

Native VLAN 1

VTP Server

VTP Client 10.1.1.2/24 GigabitEthernet0/1 2960 GigabitEthernet0/1

Si

Accounting VLAN 20

Ports: 1-8 10.1.10.0/24

Administration VLAN 10

Accounting VLAN 20

3560

Ports: 9-15 10.1.20.0/24

Ports: 9-15 10.1.20.0/24

Engineering VLAN 30 Ports: 16-24 10.1.30.0/24

WS1

WS2

10.1.30.10/24

10.1.30.10/24

Engineering VLAN 30 Ports: 16-24 10.1.30.0/24

3560 Switch enable Switch>e

Moves to privileged mode

configure terminal Switch#c

Moves to global configuration mode

hostname 3560 Switch(config)#h

Sets the host name

vtp mode server 3560(config)#v

Changes the switch to VTP server mode. Note that server is the default setting for a 3560 switch.

vtp domain bcmsn 3560(config)#v

Configures the VTP domain name to bcmsn

vtp password tower 3560(config)#v

Sets the VTP password to tower

14

Configuration Example: VLANs

vlan 10 3560(config)#v

Creates VLAN 10 and enters VLANconfiguration mode

name Admin 3560(config-vlan)#n

Assigns a name to the VLAN

exit 3560(config-vlan)#e

Increases the revision number by 1 and returns to global configuration mode

vlan 20 3560(config)#v

Creates VLAN 20 and enters VLANconfiguration mode

name Accounting 3560(config-vlan)#n

Assigns a name to the VLAN

vlan 30 3560(config-vlan)#v

Creates VLAN 30 and enters VLANconfiguration mode. Note that you do not have to exit back to global configuration mode to execute this command.

name Engineering 3560(config-vlan)#n

Assigns a name to the VLAN

exit 3560(config-vlan)#e

Increases the revision number by 1 and returns to global configuration mode

interface range 3560(config)#i fasthethernet 0/1 – 8

Enables you to set the same configuration parameters on multiple ports at the same time

switchport 3560(config-if-range)#s mode access

Sets ports 1–8 as access ports

switchport 3560(config-if-range)#s access vlan 10

Assigns ports 1–8 to VLAN 10

interface 3560(config-if-range)#i range fastethernet 0/9 – 15

Enables you to set the same configuration parameters on multiple ports at the same time

switchport 3560(config-if-range)#s mode access

Sets ports 9–15 as access ports

switchport 3560(config-if-range)#s access vlan 20

Assigns ports 9–15 to VLAN 20

interface 3560(config-if-range)#i range fastethernet 0/16 - 24

Enables you to set the same configuration parameters on multiple ports at the same time

switchport 3560(config-if-range)#s mode access

Sets ports 16–24 as access ports

Configuration Example: VLANs

15

switchport 3560(config-if-range)#s access vlan 30

Assigns ports 16–24 to VLAN 30

exit 3560(config-if-range)#e

Returns to global configuration mode

interface 3560(config)#i gigabitethernet 0/1

Moves to interface configuration mode

switchport trunk 3560(config-if)#s encapsulation dot1q

Specifies 802.1Q encapsulation on the trunk link

switchport mode 3560(config-if)#s trunk

Puts the interface into permanent trunking mode and negotiates to convert the link into a trunk link

exit 3560(config-if)#e

Returns to global configuration mode

exit 3560(config)#e

Returns to privileged mode

copy running-config startup3560#c config

Saves the configuration in NVRAM

2960 Switch enable Switch>e

Moves to privileged mode

configure terminal Switch#c

Moves to global configuration mode

hostname 2960 Switch(config)#h

Sets the host name

vtp mode client 2960(config)#v

Changes the switch to VTP client mode

vtp domain bcmsn 2960(config)#v

Configures the VTP domain name to bcmsn

interface range 2960(config)#i fastethernet 0/1 – 8

Enables you to set the same configuration parameters on multiple ports at the same time

switchport 2960(config-if-range)#s mode access

Sets ports 1–8 as access ports

switchport 2960(config-if-range)#s access vlan 10

Assigns ports 1–8 to VLAN 10

16

Configuration Example: VLANs

interface 2960(config-if-range)#i range fastethernet 0/9 – 15

Enables you to set the same configuration parameters on multiple ports at the same time

switchport 2960(config-if-range)#s mode access

Sets ports 9–15 as access ports

switchport 2960(config-if-range)#s access vlan 20

Assigns ports 9–15 to VLAN 20

interface 2960(config-if-range)#i range fastethernet 0/16 - 24

Enables you to set the same configuration parameters on multiple ports at the same time

switchport 2960(config-if-range)#s mode access

Sets ports 16–24 as access ports

switchport 2960(config-if-range)#s access vlan 30

Assigns ports 16–24 to VLAN 30

exit 2960(config-if-range)#e

Returns to global configuration mode

int gigabitethernet 0/ 2960(config)#i 1

Moves to interface configuration mode

switchport mode 2960(config-if)#s trunk

Puts the interface into permanent trunking mode and negotiates to convert the link into a trunk link

exit 2960(config-if)#e

Returns to global configuration mode

exit 2960(config)#e

Returns to privileged mode

copy running-config startup2960#c config

Saves the configuration in NVRAM

CHAPTER 3

STP and EtherChannel This chapter provides information and commands concerning the following topics: Spanning Tree Protocol • Enabling Spanning Tree Protocol (STP) • Configuring the root switch • Configuring a secondary root switch • Configuring port priority • Configuring the path cost • Configuring the switch priority of a VLAN • Configuring STP timers • Verifying STP • Optional STP configurations — PortFast — BPDU Guard — BPDU Filtering — UplinkFast — BackboneFast — Root Guard — Loop Guard — Unidirectional Link Detection (UDLD) • Changing the spanning-tree mode • Extended System ID • Enabling Rapid Spanning Tree • Enabling Multiple Spanning Tree • Verifying MST • Troubleshooting STP EtherChannel • Interface modes in EtherChannel — Without Port aggregation protocol (PAgP) or Link Aggregation Control Protocol (LACP) — With PagP — With LACP • Guidelines for configuring EtherChannel • Configuring L2 EtherChannel

18

Spanning Tree Protocol

• Configuring L3 EtherChannel • Verifying EtherChannel • Configuring EtherChannel load balancing • Types of EtherChannel load balancing • Verifying EtherChannel load balancing

Spanning Tree Protocol Enabling Spanning Tree Protocol spanning-tree vlan 5 Switch(config)#s

Enables STP on VLAN 5

no spanning-tree vlan 5 Switch(config)#n

Disables STP on VLAN 5

NOTE: If more VLANs are defined in the VLAN Trunking Protocol (VTP) than there are spanning-tree instances, you can only have STP on 64 VLANs. If you have more than 128 VLANs, it is recommended that you use Multiple STP.

Configuring the Root Switch spanning-tree Switch(config)#s vlan 5 root

Modifies the switch priority from the default 32768 to a lower value to allow the switch to become the root switch for VLAN 5 NOTE: If all other switches have extended system ID support, this switch resets its priority to 24576. If any other switch has a priority set to below 24576 already, this switch sets its own priority to 4096 less than the lowest switch priority. If by doing this the switch would have a priority of less than 1, this command fails.

spanning-tree Switch(config)#s vlan 5 root primary

Switch recalculates timers along with priority to allow the switch to become the root switch for VLAN 5 TIP: The root switch should be a backbone or distribution switch.

spanning-tree Switch(config)#s vlan 5 root primary diameter 7

Configures the switch to be the root switch for VLAN 5 and sets the network diameter to 7

Spanning Tree Protocol

19

TIP: The diameter keyword is used to define the maximum number of switches between any two end stations. The range is from 2 to 7 switches. spanning-tree Switch(config)#s vlan 5 root primary hello-time 4

Configures the switch to be the root switch for VLAN 5 and sets the hello-delay timer to 4 seconds TIP: The hello-time keyword sets the hello-delay timer to any amount between 1 and 10 seconds. The default time is 2 seconds.

Configuring a Secondary Root Switch spanning-tree Switch(config)#s vlan 5 root secondary

Switch recalculates timers along with priority to allow the switch to become the root switch for VLAN 5 should the primary root switch fail NOTE: If all other switches have extended system ID support, this switch resets its priority to 28672. Therefore, if the root switch fails, and all other switches are set to the default priority of 32768, this becomes the new root switch. For switches without Extended System ID support, the switch priority is changed to 16384.

spanning-tree Switch(config)#s vlan 5 root secondary diameter 7

Configures the switch to be the secondary root switch for VLAN 5 and sets the network diameter to 7

spanning-tree Switch(config)#s vlan 5 root secondary hello-time 4

Configures the switch to be the secondary root switch for VLAN 5 and sets the hellodelay timer to 4 seconds

Configuring Port Priority interface Switch(config)#i gigabitethernet 0/1

Moves to interface configuration mode

spanning-tree Switch(config-if)#s port-priority 64

Configures the port priority for the interface that is an access port

20

Spanning Tree Protocol

spanning-tree Switch(config-if)#s vlan 5 port-priority 64

Configures the VLAN port priority for an interface that is a trunk port NOTE: Port priority is used to break a tie when two switches have equal priorities for determining the root switch. The number can be between 0 and 255. The default port priority is 128. The lower the number, the higher the priority.

Configuring the Path Cost interface Switch(config)#i gigabitethernet 0/1

Moves to interface config mode

spanning-tree Switch(config-if)#s cost 100000

Configures the cost for the interface that is an access port

spanning-tree Switch(config-if)#s vlan 5 cost 1000000

Configures the VLAN cost for an interface that is a trunk port NOTE: If a loop occurs, STP uses the path cost when trying to determine which interface to place into the forwarding state. A higher path cost means a lower speed transmission. The range of the cost keyword is 1 through 200000000. The default is based on the media speed of the interface.

Configuring the Switch Priority of a VLAN spanning-tree vlan Switch(config)#s 5 priority 12288

Configures the switch priority of VLAN 5 to 12288

NOTE: With the priority keyword, the range is 0 to 61440 in increments of 4096. The default is 32768. The lower the priority, the more likely the switch will be chosen as the root switch. Only the following numbers can be used as a priority value:

0

4096

8192

12288

16384

20480

24576

28672

32768

36864

40960

45056

49152

53248

57344

61440

Spanning Tree Protocol

21

CAUTION: Cisco recommends caution when using this command. Cisco further recommends that the spanning-tree vlan x root primary or the spanning-tree vlan x root secondary command be used instead to modify the switch priority.

Configuring STP Timers spanning-tree vlan Switch(config)#s 5 hello-time 4

Changes the hello-delay timer to 4 seconds on VLAN 5

spanning-tree vlan Switch(config)#s 5 forward-time 20

Changes the forward-delay timer to 20 seconds on VLAN 5

spanning-tree vlan Switch(config)#s 5 max-age 25

Changes the maximum-aging timer to 25 seconds on VLAN 5

NOTE: For the hello-time command, the range is 1 to 10 seconds. The default is 2 seconds. For the forward-time command, the range is 4 to 30 seconds. The default is 15 seconds. For the max-age command, the range is 6 to 40 seconds. The default is 20 seconds.

CAUTION: Cisco recommends caution when using this command. Cisco further recommends that the spanning-tree vlan x root primary or the spanning-tree vlan x root secondary command be used instead to modify the switch timers.

Verifying STP show spanning-tree Switch#s

Displays STP information

show spanning-tree active Switch#s

Displays STP information on active interfaces only

show spanning-tree brief Switch#s

Displays a brief status of the STP

show spanning-tree detail Switch#s

Displays a detailed summary of interface information

show spanning-tree Switch#s interface gigabitethernet 0/1

Displays STP information for interface gigabitethernet 0/1

show spanning-tree summary Switch#s

Displays a summary of port states

s h o w s p a n n i n g - t r e e s u m m a ry Switch#s totals

Displays the total lines of the STP section

show spanning-tree vlan 5 Switch#s

Displays STP information for VLAN 5

22

Spanning Tree Protocol

Optional STP Configurations Although the following commands are not mandatory for STP to work, you might find these helpful in fine-tuning your network.

PortFast interface Switch(config)#i fastethernet 0/10

Moves to interface config mode

spanning-tree Switch(config-if)#s portfast

Enables PortFast on an access port

spanning-tree Switch(config-if)#s portfast trunk

Enables PortFast on a trunk port WARNING: Use the portfast command only when connecting a single end station to an access or trunk port. Using this command on a port connected to a switch or hub could prevent spanning tree from detecting loops. NOTE: If you enable the voice VLAN feature, PortFast is enabled automatically. If you disable voice VLAN, PortFast is still enabled.

show spanning-tree Switch#s interface fastethernet 0/10 portfast

Displays PortFast information on interface fastethernet 0/10

BPDU Guard spanning-tree Switch(config)#s portfast bpduguard default

Globally enables BPDU Guard

interface range Switch(config)#i fastethernet 0/1 – 5

Enters interface range configuration mode

Switch(config-ifspanning-tree portfast range)#s

Enables PortFast on all interfaces in the range NOTE: By default, BPDU Guard is disabled.

errdisable Switch(config)#e recovery cause bpduguard

Allows port to reenable itself if the cause of the error is BPDU Guard by setting a recovery timer

Spanning Tree Protocol

23

errdisable Switch(config)#e recovery interval 400

Sets recovery timer to 400 seconds. Default is 300 seconds. Range is from 30 to 86400 seconds

show spanning-tree Switch#s summary totals

Verifies whether BPDU Guard is enabled or disabled

show errdisable recovery Switch#s

Displays errdisable recovery timer information

BPDU Filtering spanning-tree Switch(config)#s portfast bpdufilter default

Globally enables BPDU Filtering— prevents ports in PortFast from sending or receiving bridge protocol data units (BPDU)

interface range Switch(config)#i fastethernet 0/1 – 5

Enters interface range config mode

spanningSwitch(config-if-range)#s tree portfast

Enables PortFast on all interfaces in the range NOTE: By default, BPDU Filtering is disabled. CAUTION: Enabling BPDU Filtering on an interface, or globally, is the same as disabling STP, which can result in spanning-tree loops being created but not detected.

interface Switch(config)#i fastethernet 0/15

Moves to interface config mode

spanning-tree Switch(config-if)#s bpdufilter enable

Enables BPDU Filtering on the interface without enabling the PortFast feature

show running-config Switch#s

Verifies BPDU Filtering is enabled on interfaces

24

Spanning Tree Protocol

UplinkFast spanning-tree Switch(config)#s uplinkfast

Enables UplinkFast

spanning-tree Switch(config)#s uplinkfast max-update-rate 200

Enables UplinkFast and sets the update packet rate to 200 packets/second NOTE: UplinkFast cannot be set on an individual VLAN. The spanning-tree uplinkfast command affects all VLANs. NOTE: For the max-update-rate argument, the range is 0 to 32000 packets/second. The default is 150. If you set the rate to 0, station-learning frames are not generated. This will cause STP to converge more slowly after a loss of connectivity.

show spanning-tree summary Switch#s

Verifies UplinkFast has been enabled

NOTE: UplinkFast cannot be enabled on VLANs that have been configured for switch priority.

NOTE: UplinkFast is most useful in access-layer switches, or switches at the edge of the network. It is not appropriate for backbone devices.

BackboneFast spanning-tree Switch(config)#s backbonefast

Enables BackboneFast

show spanning-tree summary Switch#s

Verifies BackboneFast has been enabled

Root Guard interface Switch(config)#i fastethernet 0/1

Moves to interface config mode

spanning-tree Switch(config-if)#s guard root

Enables Root Guard on the interface

show running-config Switch#s

Verifies Root Guard is enabled on the interface

Spanning Tree Protocol

25

NOTE: You cannot enable both Root Guard and Loop Guard at the same time.

NOTE: Root Guard enabled on an interface applies to all VLANs to which the interface belongs.

NOTE: Do not enable Root Guard on interfaces to be used by the UplinkFast feature.

Loop Guard show spanning-tree active Switch#s

Shows which ports are alternate or root ports

show spanning-tree mst Switch#s

Shows which ports are alternate or root ports

configure terminal Switch#c

Moves to global configuration mode

spanning-tree Switch(config)#s loopguard default

Enables Loop Guard globally on the switch

exit Switch(config)#e

Returns to privileged mode

show running-config Switch#s

Verifies that Loop Guard has been enabled

NOTE: You cannot enable both Root Guard and Loop Guard at the same time.

NOTE: This feature is most effective when it is configured on the entire switched network.

NOTE: Loop Guard operates only on ports that are considered to be point to point by the STP.

Unidirectional Link Detection udld enable Switch(config)#u

Enables Unidirectional Link Detection (UDLD) on all fiber-optic Interfaces NOTE: By default, UDLD is disabled.

interface Switch(config)#i fastethernet 0/24

Moves to interface config mode

26

Spanning Tree Protocol

udld port Switch(config-if)#u

Enables UDLD on this interface—required for copper-based interfaces NOTE: On a fiber-optic (FO) interface, the interface command udld port overrides the global command udld enable. Therefore, if you issue the command no udld port on an FO interface, you will still have the globally enabled udld enable command to deal with.

show udld Switch#s

Displays UDLD information

show udld interface Switch#s fastethernet 0/1

Displays UDLD information for interface fastethernet 0/1

udld reset Switch#u

Resets all interfaces shut down by UDLD NOTE: You can also use the shutdown command, followed by a no shutdown command in interface config mode, to restart a disabled interface.

Changing the Spanning-Tree Mode There are different types of spanning tree that can be configured on a Cisco switch. The options vary according to the platform: • Per-VLAN Spanning Tree (PVST)—There is one instance of spanning tree for each VLAN. This is a Cisco proprietary protocol. • Per-VLAN Spanning Tree Plus (PVST+)—Also Cisco proprietary. Has added extensions to the PVST protocol. • Rapid PVST+—This mode is the same as PVST+ except that it uses a rapid convergence based on the 802.1w standard. • Multiple Spanning Tree Protocol (MSTP)—IEEE 802.1s. Extends the 802.1w Rapid Spanning Tree (RST) algorithm to multiple spanning trees. Multiple VLANs can map to a single instance of RST. You cannot run MSTP and PVST at the same time. spanning-tree mode mst Switch(config)#s

Enables MSTP. This command is available only on a switch running the EI software image.

spanning-tree mode pvst Switch(config)#s

Enables PVST—this is the default setting

spanning-tree mode Switch(config)#s rapid-pvst

Enables Rapid PVST+

Spanning Tree Protocol

27

Extended System ID spanning-tree extend Switch(config)#s system-id

Enables Extended System ID, also known as MAC Address Reduction NOTE: Catalyst switches running software earlier than Cisco IOS Release 12.1(8)EA1 do not support the Extended System ID.

show spanning-tree summary Switch#s

Verifies Extended System ID is enabled

show running-config Switch#s

Verifies Extended System ID is enabled

Enabling Rapid Spanning Tree spanning-tree mode Switch(config)#s rapid-pvst

Enables Rapid PVST+

interface Switch(config)#i fastethernet 0/1

Moves to interface config mode

spanning-tree Switch(config-if)#s link-type point-to-point

Sets the interface to be a point-to-point interface NOTE: By setting the link type to point-to-point, this means that if you connect this port to a remote port, and this port becomes a designated port, the switch will negotiate with the remote port and transition the local port to a forwarding state.

exit Switch(config-if)#e clear spanning-tree Switch(config)#c detected-protocols

NOTE: The clear spanning-tree detected-protocols command restarts the protocol migration process on the switch if any port is connected to a port on a legacy 802.1D switch.

28

Spanning Tree Protocol

Enabling Multiple Spanning Tree spanning-tree mst Switch(config)#s configuration

Enters MST config mode

instance 1 vlan 4 Switch(config-mst)#i

Maps VLAN 4 to an Multiple Spanning Tree (MST) instance

instance 1 vlan Switch(config-mst)#i 1-15

Maps VLANs 1–15 to MST instance 1

instance 1 vlan Switch(config-mst)#i 10,20,30

Maps VLANs 10, 20, and 30 to MST instance 1 NOTE: For the instance x vlan y command, the instance must be a number between 1 and 15, and the VLAN range is 1 to 4094.

name region12 Switch(config-mst)#n

Specifies the configuration name to be region12. NOTE: The name argument can be up to 32 characters long and is case sensitive.

revision 4 Switch(config-mst)#r

Specifies the revision number NOTE: The range for the revision argument is 0 to 65535.

show pending Switch(config-mst)#s

Verifies the configuration by displaying a summary of what you have configured for the MST region

exit Switch(config-mst)#e

Applies all changes and returns to global config mode

spanning-tree mst 1 Switch(config)#s

Enables MST CAUTION: Changing spanning-tree modes can disrupt traffic because all spanning-tree instances are stopped for the old mode and restarted in the new mode. NOTE: You cannot run both MSTP and PVST at the same time.

spanning-tree mst 1 Switch(config)#s root primary

Configures a switch as a primary root switch within MST instance 1. The primary root switch priority is 24576.

Spanning Tree Protocol

29

spanning-tree mst 1 Switch(config)#s root secondary

Configures a switch as a secondary root switch within MST instance 1. The secondary root switch priority is 28672.

exit Switch(config)#e

Returns to privileged mode

Verifying MST show spanning-tree mst Switch#s configuration

Displays the MST region configuration

show spanning-tree mst 1 Switch#s

Displays the MST information for instance 1

show spanning-tree mst Switch#s interface fastethernet 0/1

Displays the MST information for interface fastethernet 0/1

show spanning-tree mst 1 Switch#s interface fastethernet 0/1

Displays the MST information for instance 1 on interface fastethernet 0/1

show spanning-tree mst 1 Switch#s detail

Shows detailed information about MST instance 1

Troubleshooting Spanning Tree debug spanning-tree all Switch#d

Displays all spanning-tree debugging events

debug spanning-tree events Switch#d

Displays spanning-tree debugging topology events

debug spanning-tree Switch#d backbonefast

Displays spanning-tree debugging BackboneFast events

debug spanning-tree Switch#d uplinkfast

Displays spanning-tree debugging UplinkFast event

debug spanning-tree mstp all Switch#d

Displays all MST debugging events

debug spanning-tree switch Switch#d state

Displays spanning-tree port state changes

debug spanning-tree pvst+ Switch#d

Displays PVST+ events

30

Spanning Tree Protocol

Configuration Example: STP Figure 3-1 shows the network topology for the configuration that follows, which shows how to configure STP using commands covered in this chapter. Figure 3-1

Network Topology for STP Configuration Example VTP Domain STPDEMO Fa0/13 Fa0/8 G0/1

UDLD Enabled VTP Client VLAN 10 Root Primary Distribution1 (3560)

1

10

1

Fa0/8

20

1

Fa0/5

G0/2 20

Fa0/5

Fa0/2 1 10

1

Fa0/1

10 20 G0/2

Fa 0

G0/1

Fa 0

/3

/4

10

Ro

ot

Ro

ot

UDLD Enabled VTP Client VLAN 20 Root Primary Distribution2 (3560)

20

Core (3560) VLAN 1 Root Primary VTP Server UDLD Enabled

G0/1

Fa0/6

G0/2

Gu

ard

Fa0/6

1

Fa0/8

10 20

Fa0/3 20 Root Guard

Fa0/4 Root Guard

Gu

ard

20

10

Fa0/1 Fa0/2

Access1 (2960) VTP Client UDLD Enabled

G0/2

1

20

1

10

G0/1

Fa0/5 Root Guard

Access2

20 10

Fa 0

Fa0/3

/1

Fa 0

/2

10

1

Fa0/4

20

Fa0/5 10 20

Access2

Fa0/8

VLAN 10 - Forwarding

We do not want Access2 to ever become the Root Switch.

Fa0/8

Access2 (2960) VTP Client

VLAN 20 - Blocking

Core Switch (3560) enable Switch>e

Moves to privileged mode

configure terminal Switch#c

Moves to global config mode

hostname Core Switch(config)#h

Sets host name

no ip domain-lookup Core(config)#n

Turns off Dynamic Name System (DNS) queries so that spelling mistakes will not slow you down

vtp mode server Core(config)#v

Changes the switch to VTP server mode. This is the default mode.

Spanning Tree Protocol

vtp domain stpdemo Core(config)#v

Configures the VTP domain name to stpdemo

vlan 10 Core(config)#v

Creates VLAN 10 and enters VLANconfig mode

name Accounting Core(config-vlan)#n

Assigns a name to the VLAN

exit Core(config-vlan)#e

Returns to global config mode

vlan 20 Core(config)#v

Creates VLAN 20 and enters VLANconfig mode

name Marketing Core(config-vlan)#n

Assigns a name to the VLAN

exit Core(config-vlan)#e

Returns to global config mode

spanning-tree vlan 1 Core(config)#s root primary

Configures the sitch to become the root switch for VLAN 1

udld enable Core(config)#u

Enables UDLD

exit Core(config)#e

Returns to privileged mode

copy running-config startupCore#c config

Saves the configuration to NVRAM

31

Distribution 1 Switch (3560) enable Switch>e

Moves to privileged mode

configure terminal Switch#c

Moves to global config mode

hostname Distribution1 Switch(config)#h

Sets host name

no ip domainDistribution1(config)#n lookup

Turns off DNS queries so that spelling mistakes will not slow you down

vtp domain Distribution1(config)#v stpdemo

Configures the VTP domain name to stpdemo

vtp mode client Distribution1(config)#v

Changes the switch to VTP client mode

spanning-tree Distribution1(config)#s vlan 10 root primary

Configures the switch to become the root switch of VLAN 10

udld enable Distribution1(config)#u

Enables UDLD on all FO interfaces

32

Spanning Tree Protocol

interface range Distribution1(config)#i fastethernet 0/3 – 4

Moves to interface range mode

spanningDistribution1(config-if)#s tree guard root

Prevents switch on the other end of the link (Access2) from becoming the root switch

exit Distribution1(config-if)#e

Returns to global config mode

exit Distribution1(config)#e

Returns to privileged mode

copy running-config Distribution1#c startup-config

Saves the configuration to NVRAM

Distribution 2 Switch (3560) enable Switch>e

Moves to privileged mode

configure terminal Switch#c

Moves to global config mode

hostname Switch(config)#h Distribution2

Sets host name

no ip domainDistribution2(config)#n lookup

Turns off DNS queries so that spelling mistakes will not slow you down

vtp domain Distribution2(config)#v stpdemo

Configures the VTP domain name to stpdemo

vtp mode Distribution2(config)#v client

Changes the switch to VTP client mode

spanning-tree Distribution2(config)#s vlan 20 root primary

Configures the switch to become the root switch of VLAN 20

udld enable Distribution2(config)#u

Enables UDLD on all FO interfaces

interface Distribution2(config)#i range fastethernet 0/3 – 4

Moves to interface range mode

spanningDistribution2(config-if)#s tree guard root

Prevents the switch on the other end of link (Access2) from becoming the root switch

exit Distribution2(config-if)#e

Returns to global config mode

exit Distribution2(config)#e

Returns to privileged mode

copy running-config Distribution2#c startup-config

Saves the configuration to NVRAM

Spanning Tree Protocol

33

Access 1 Switch (2960) enable Switch>e

Moves to privileged mode

configure terminal Switch#c

Moves to global config mode

hostname Access1 Switch(config)#h

Sets host name

no ip domain-lookup Access1(config)#n

Turns off DNS queries so that spelling mistakes will not slow you down

vtp domain stpdemo Access1(config)#v

Configures the VTP domain name to stpdemo

vtp mode client Access1(config)#v

Changes the switch to VTP client mode

interface range Access1(config)#i fastethernet 0/6 – 12

Moves to interface range config mode

switchport Access1(config-if-range)#s mode access

Places all interfaces in access mode

spanningAccess1(config-if-range)#s tree portfast

Places all ports directly into forwarding mode

spanningAccess1(config-if-range)#s tree bpduguard enable

Enables BPDU Guard

exit Access1(config-if-range)#e

Moves back to global config mode

spanning-tree Access1(config)#s uplinkfast

Enables UplinkFast to reduce STP convergence time

interface Access1(config)#i fastethernet 0/5

Moves to interface config mode

spanning-tree Access1(config-if)#s guard root

Prevents the switch on the other end of link (Access2) from becoming the root switch

exit Access1(config-if)#e

Returns to global config mode

udld enable Access1(config)#u

Enables UDLD on all FO interfaces

exit Access1(config)#e

Returns to privileged mode

copy running-config Access1#c startup-config

Saves the configuration to NVRAM

34

EtherChannel

Access 2 Switch (2960) enable Switch>e

Moves to privileged mode

configure terminal Switch#c

Moves to global config mode

hostname Access2 Switch(config)#h

Sets host name

no ip domain-lookup Access2(config)#n

Turns off DNS queries so that spelling mistakes will not slow you down

vtp domain stpdemo Access2(config)#v

Configures the VTP domain name to stpdemo

vtp mode client Access2(config)#v

Changes the switch to VTP client mode

interface range Access2(config)#i fastethernet 0/6 – 12

Moves to interface range config mode

switchport Access2(config-if-range)#s mode access

Places all interfaces in access mode

spanningAccess2(config-if-range)#s tree portfast

Places all ports directly into forwarding mode

spanningAccess2(config-if-range)#s tree bpduguard enable

Enables BPDU Guard

exit Access2(config-if-range)#e

Moves back to global config mode

spanning-tree vlan Access2(config)#s 10 priority 61440

Ensures this switch will not become the root switch for VLAN 10

exit Access2(config)#e

Returns to privileged mode

copy running-config Access2#c startup-config

Saves config to NVRAM

EtherChannel EtherChannel provides fault-tolerant high-speed links between switches, routers, and servers. An EtherChannel consists of individual Fast Ethernet or Gigabit Ethernet links bundled into a single logical link. If a link within an EtherChannel fails, traffic previously carried over that failed link changes to the remaining links within the EtherChannel.

EtherChannel

35

Interface Modes in EtherChannel Mode

Protocol

Description

On

None

Forces the interface into an EtherChannel without PAgP or LACP. Channel only exists if connected to another interface group also in On mode.

Auto

PAgP

Places the interface into a passive negotiating state—will respond to PAgP packets, but will not initiate PAgP negotiation

Desirable

PAgP

Places the interface into an active negotiating state—will send PAgP packets to start negotiations

Passive

LACP

Places the interface into a passive negotiating state—will respond to LACP packets, but will not initiate LACP negotiation

Active

LACP

Place the interface into an active negotiating state—will send LACP packets to start negotiations

Guidelines for Configuring EtherChannel • PAgP is Cisco proprietary. • LACP is defined in 802.3ad. • Can combine from two to eight parallel links. • All ports must be identical: — Same speed and duplex — Cannot mix Fast Ethernet and Gigabit Ethernet — Cannot mix PAgP and LACP — Must all be VLAN trunk or nontrunk operational status • All links must be either L2 or L3 in a single channel group. • To create a channel in PAgP, sides must be set to — Auto-Desirable — Desirable-Desirable • To create a channel in LACP, sides must be set to — Active-Active — Active-Passive • To create a channel without using PAgP or LACP, sides must be set to On-On. • Do not configure a GigaStack Gigabit Interface Converter (GBIC) as part of an EtherChannel. • An interface that is already configured to be a Switched Port Analyzer (SPAN) destination port will not join an EtherChannel group until SPAN is disabled. • Do not configure a secure port as part of an EtherChannel.

36

EtherChannel

• Interfaces with different native VLANs cannot form an EtherChannel. • When using trunk links, ensure all trunks are in the same mode—Inter-Switch Link (ISL) or Dot1Q.

Configuring L2 EtherChannel interface range Switch(config)#i fastethernet 0/1 - 4

Moves to interface range config mode

channelSwitch(config-if-range)#c protocol pagp

Specifies the PAgP protocol to be used in this channel

or channelSwitch(config-if-range)#c protocol lacp

Specifies the LACP protocol to be used in this channel

channelSwitch(config-if-range)#c desirable | auto | on group 1 mode {d | passive | active }

Creates channel group 1 and assigns interfaces 01–04 as part of it. Use whichever mode is necessary, depending on your choice of protocol.

Configuring L3 EtherChannel interface port3560Switch(config)#i channel 1

Creates the port-channel logical interface, and moves to interface config mode. Valid channel numbers are 1–48.

no 3560Switch(config-if)#n switchport

Puts the interface into Layer 3 mode

ip address 3560Switch(config-if)#i 172.16.10.1 255.255.255.0

Assigns IP address and netmask

exit 3560Switch(config-if)#e

Moves to global config mode

interface range 3560Switch(config)#i fastethernet 0/20 – 24

Moves to interface range config mode

no ip 3560Switch(config-if-range)#n address

Ensures there are no IP addresses assigned on the interfaces

3560Switch(config-ifchannel-protocol pagp range)#c

Specifies the PAgP protocol to be used in this channel

EtherChannel

37

3560Switch(config-ifchannel-protocol lacp range)#c

Specifies the LACP protocol to be used in this channel

3560Switch(config-ifrange)#channel-group 1 mode {desirable | auto | on | passive | active }

Creates channel group 1 and assigns interfaces 20–24 as part of it. Use whichever mode is necessary, depending on your choice of protocol. NOTE: The channel group number must match the port channel number.

Verifying EtherChannel show running-config Switch#s

Displays list of what is currently running on the device

show running-config Switch#s interface fastethernet 0/12

Displays interface fastethernet 0/12 information

show interfaces Switch#s fastethernet 0/12 etherchannel

Displays L3 EtherChannel information

show etherchannel Switch#s

Displays all EtherChannel information

show etherchannel 1 portSwitch#s channel

Displays port channel information

show etherchannel summary Switch#s

Displays a summary of EtherChannel information

show pagp neighbor Switch#s

Shows PAgP neighbor information

clear pagp 1 counters Switch#c

Clears PAgP channel group 1 information

clear lacp 1 counters Switch#c

Clears LACP channel group 1 information

port-channel loadSwitch(config)#p balance type

Configures load balancing of method named type

38

EtherChannel

NOTE: The following methods are allowed when load balancing across a port channel: dst-ip Distribution is based on destination host IP address. dst-mac Distribution is based on the destination MAC address. Packets to the same destination are sent on the same port, but packets to different destinations are sent on different ports in the channel. src-dst-ip Distribution is based on source and destination host IP address. src-dst-mac Distribution is based on source and destination MAC address. src-ip Distribution is based on source IP address. src-mac Distribution is based on source MAC address. Packets from different hosts use different ports in the channel, but packets from the same host use the same port. show etherchannel loadSwitch#s balance

Displays EtherChannel load-balancing information

Configuration Example: EtherChannel Figure 3-2 shows the network topology for the configuration that follows, which shows how to configure EtherChannel using commands covered in this chapter. Figure 3-2

Network Topology for EtherChannel Configuration FEC IEEE 802.1q Trunk

DLSwitch (3560)

FEC IEEE 802.1q Trunk

ALSwitch1 (2960)

Fa0/6

ALSwitch2 (2960)

Fa0/1

Fa0/1

Fa0/3

Fa0/1

Fa0/2

Fa0/2

Fa0/4

Fa0/2

Fa0/12

Fa0/6

Fa0/12

Accounting VLAN 10 Fa 0/5-8 172.16.10.0/24

Marketing VLAN 20 Fa 0/9-12 172.16.20.0/24

Accounting VLAN 10 Fa 0/5-8 172.16.10.0/24

Marketing VLAN 20 Fa 0/9-12 172.16.20.0/24

WS1

WS2

WS3

WS4

172.16.10.2/24

172.16.20.2/24

172.16.10.3/24

172.16.20.3/24

EtherChannel

DLSwitch (3560) enable Switch>e

Moves to privileged mode

configure terminal Switch#c

Moves to global config mode

hostname DLSwitch Switch(config)#h

Sets host name

no ip domain-lookup DLSwitch(config)#n

Turns off DNS queries so that spelling mistakes will not slow you down

vtp mode server DLSwitch(config)#v

Changes the switch to VTP server mode

vtp domain DLSwitch(config)#v testdomain

Configures the VTP domain name to testdomain

vlan 10 DLSwitch(config)#v

Creates VLAN 10 and enters VLANconfig mode

name DLSwitch(config-vlan)#n Accounting

Assigns a name to the VLAN

exit DLSwitch(config-vlan)#e

Returns to global config mode

vlan 20 DLSwitch(config)#v

Creates VLAN 20 and enters VLANconfig mode

name Marketing DLSwitch(config-vlan)#n

Assigns a name to the VLAN

exit DLSwitch(config-vlan)#e

Returns to global config mode

interface range DLSwitch(config)#i fastethernet 0/1 – 4

Moves to interface range config mode

switchport trunk DLSwitch(config-if)#s encapsulation dot1q

Specifies 802.1Q encapsulation on the trunk link

switchport mode DLSwitch(config-if)#s trunk

Puts the interface into permanent trunking mode and negotiates to convert the link into a trunk link

exit DLSwitch(config-if)#e

Returns to global config mode

interface range DLSwitch(config)#i fastethernet 0/1 – 2

Moves to interface range config mode

channel-group 1 DLSwitch(config-if)#c mode desirable

Creates channel group 1 and assigns interfaces 01–02 as part of it

exit DLSwitch(config-if)#e

Moves to global config mode

39

40

EtherChannel

interface range DLSwitch(config)#i fastethernet 0/3 – 4

Moves to interface range config mode

channel-group 2 DLSwitch(config-if)#c mode desirable

Creates channel group 2 and assigns interfaces 03–04 as part of it

exit DLSwitch(config-if)#e

Moves to global config mode

port-channel loadDLSwitch(config)#p balance dst-mac

Configures load balancing based on destination MAC address

exit DLSwitch(config)#e

Moves to privileged mode

copy running-config DLSwitch#c startup-config

Saves the configuration to NVRAM

ALSwitch1 (2960) enable Switch>e

Moves to privileged mode

configure terminal Switch#c

Moves to global config mode

hostname ALSwitch1 Switch(config)#h

Sets host name

no ip domainALSwitch1(config)#n lookup

Turns off DNS queries so that spelling mistakes will not slow you down

vtp mode client ALSwitch1(config)#v

Changes the switch to VTP client mode

vtp domain ALSwitch1(config)#v testdomain

Configures the VTP domain name to testdomain

interface range ALSwitch1(config)#i fastethernet 0/5 – 8

Moves to interface range config mode

ALSwitch1(config-ifswitchport mode access range)#s

Sets ports 5–8 as access ports

ALSwitch1(config-ifswitchport access vlan 10 range)#s

Assigns ports to VLAN 10

exit ALSwitch1(config-if-range)#e

Moves to global config mode

interface range ALSwitch1(config)#i fastethernet 0/9 – 12

Moves to interface range config mode

ALSwitch1(config-ifswitchport mode access range)#s

Sets ports 9–12 as access ports

ALSwitch1(config-ifswitchport access vlan 20 range)#s

Assigns ports to VLAN 20

EtherChannel

exit ALSwitch1(config-if-range)#e

Moves to global config mode

interface range ALSwitch1(config)#i fastethernet 0/1 – 2

Moves to interface range config mode

ALSwitch1(config-ifswitchport mode trunk range)#s

Puts the interface into permanent trunking mode and negotiates to convert the link into a trunk link

channelALSwitch1(config-if-range)#c group 1 mode desirable

Creates Channel Group 1 and assigns interfaces 01–02 as part of it

exit ALSwitch1(config-if-range)#e

Moves to global config mode

exit ALSwitch1(config)#e

Moves to privileged mode

copy running-config ALSwitch1#c startup-config

Saves the configuration to NVRAM

41

ALSwitch2 (2960) enable Switch>e

Moves to privileged mode

configure terminal Switch#c

Moves to global config mode

hostname ALSwitch2 Switch(config)#h

Sets host name

no ip domainALSwitch2(config)#n lookup

Turns off DNS queries so that spelling mistakes will not slow you down

vtp mode client ALSwitch2(config)#v

Changes the switch to VTP client mode

vtp domain ALSwitch2(config)#v testdomain

Configures the VTP domain name to testdomain

interface range ALSwitch2(config)#i fastethernet 0/5 – 8

Moves to interface range config mode

ALSwitch2(config-ifswitchport mode access range)#s

Sets ports 5–8 as access ports

ALSwitch2(config-ifswitchport access vlan 10 range)#s

Assigns ports to VLAN 10

exit ALSwitch2(config-if-range)#e

Moves to global config mode

42

EtherChannel

interface range ALSwitch2(config)#i fastethernet 0/9 – 12

Moves to interface range config mode

ALSwitch2(config-ifswitchport mode access range)#s

Sets ports 9–12 as access ports

ALSwitch2(config-ifswitchport access vlan 20 range)#s

Assigns ports to VLAN 20

exit ALSwitch2(config-if-range)#e

Moves to global config mode

interface range ALSwitch2(config)#i fastethernet 0/1 – 2

Moves to interface range config mode

ALSwitch2(config-ifswitchport mode trunk range)#s

Puts the interface into permanent trunking mode and negotiates to convert the link into a trunk link

channelALSwitch2(config-if-range)#c group 1 mode desirable

Creates channel group 1 and assigns interfaces 01–02 as part of it.

exit ALSwitch2(config-if-range)#e

Moves to global config mode

exit ALSwitch2(config)#e

Moves to privileged mode

copy running-config ALSwitch2#c startup-config

Saves the configuration to NVRAM

CHAPTER 4

Inter-VLAN Routing This chapter provides information and commands concerning the following topics: • Configuring Cisco Express Forwarding (CEF) • Verifying CEF • Troubleshooting CEF • Inter-VLAN communication using an external router: router-on-a-stick • Inter-VLAN communication tips • Inter-VLAN communication on a multilayer switch through a switch virtual interface — Removing L2 switchport capability of a switch port — Configuring inter-VLAN communication

Configuring Cisco Express Forwarding ip cef Switch(config)#i

Enables standard CEF

ip cef distributed Switch(config)#i

Enables distributed CEF (dCEF)

no ip cef Switch(config)#n

Disables CEF globally

interface fastethernet Switch(config)#i 0/1

Moves to interface configuration mode

ip route-cache cef Switch(config-if)#i

Enables CEF on the interface

44

Troubleshooting CEF

Verifying CEF show ip cef Switch#s

Displays entries in the Forwarding Information Base (FIB)

show ip cef summary Switch#s

Displays a summary of the FIB

show ip cef unresolved Switch#s

Displays unresolved FIB entries

show ip cef fastethernet 0/1 Switch#s

Displays the FIB entry for the specified interface

show ip cef fastethernet 0/1 Switch#s detail

Displays detailed information about the FIB for the interface

show interface fastethernet Switch#s 0/1 | begin L3

Displays switching statistics for the interface beginning at the section for L3

show interface Switch#s gigabitethernet 1/1 | include switched

Displays switching statistics that show statistics for each layer

show adjacency fastethernet Switch#s 0/20 detail

Displays the content of the information to be used during L2 encapsulation

show cef drop Switch#s

Display packets that are dropped because adjacencies are incomplete or nonexistent

show ip interface vlan10 Switch#s

Verifies whether CEF is enabled on an interface

Troubleshooting CEF debug ip cef Switch#d

Displays debug information for CEF

debug ip cef drop Switch#d

Displays debug information about dropped packets

debug ip cef access-list x Switch#d

Displays information from specified access lists

debug ip cef receive Switch#d

Displays packets that are not switched using information from the FIB but that are received and sent to the next switching layer

debug ip cef events Switch#d

Displays general CEF events

Inter-VLAN Communication Using an External Router: Router-on-a-Stick

debug ip cef prefix-ipc Switch#d

Displays updates related to IP prefix information

debug ip cef table Switch#d

Produces a table showing events related to the FIB table

ping ip Switch#p

Performs an extended ping

45

Inter-VLAN Communication Using an External Router: Router-on-a-Stick interface Router(config)#i fastethernet 0/0

Moves to interface configuration mode

duplex full Router(config-if)#d

Sets interface to full duplex

no shutdown Router(config-if)#n

Enables interface

interface Router(config-if)#i fastethernet 0/0.1

Creates subinterface 0/0.1 and moves to subinterface configuration mode

description Router(config-subif)#d Management VLAN 1

(Optional) Sets locally significant descriptor of the subinterface

encapsulation Router(config-subif)#e dot1q 1 native

Assigns VLAN 1 to this subinterface. VLAN 1 will be the native VLAN. This subinterface will use the 802.1Q trunking protocol.

ip address Router(config-subif)#i 192.168.1.1 255.255.255.0

Assigns IP address and netmask

int Router(config-subif)#i fastethernet 0/0.10

Creates subinterface 0/0.10 and moves to subinterface configuration mode

description Router(config-subif)#d Accounting VLAN 10

(Optional) Sets locally significant descriptor of the subinterface

encapsulation Router(config-subif)#e dot1q 10

Assigns VLAN 10 to this subinterface. This subinterface will use the 802.1Q trunking protocol.

ip address Router(config-subif)#i 192.168.10.1 255.255.255.0

Assigns IP address and netmask

exit Router(config-subif)#e

Returns to interface configuration mode

exit Router(config-if)#e

Returns to global configuration mode

Router(config)#

46

Inter-VLAN Communication on a Multilayer Switch Through a Switch Virtual…

NOTE: The subnets of the VLANs are directly connected to the router. Routing between these subnets does not require a dynamic routing protocol. In a more complex topology, these routes would need to either be advertised with whatever dynamic routing protocol is being used, or be redistributed into whatever dynamic routing protocol is being used.

NOTE: Routes to the subnets associated with these VLANs will appear in the routing table as directly connected networks.

Inter-VLAN Communication Tips • Although most routers support both Inter-Switch Link (ISL) and Dot1Q encapsulation some switch models only support Dot1Q, such as the 2950 and 2960 series. • If you need to use ISL as your trunking protocol, use the command encapsulation isl x, where x is the number of the VLAN to be assigned to that subinterface. • Recommended best practice is to use the same number of the VLAN number for the subinterface number. It is easier to troubleshoot VLAN 10 on subinterface fa0/0.10 than on fa0/0.2 • The native VLAN (usually VLAN 1) cannot be configured on a subinterface for Cisco IOS releases that are earlier than 12.1(3)T. Native VLAN IP addresses will therefore need to be configured on the physical interface. Other VLAN traffic will be configured on subinterfaces: int fastethernet 0/0 Router(config)#i encapsulation dot1q 1 native Router(config-if)#e ip address 192.168.1.1 255.255.255.0 Router(config-if)#i int fastethernet 0/0.10 Router(config-if)#i encapsulation dot1q 10 Router(config-subif)#e ip address 192.168.10.1 255.255.255.0 Router(config-subif)#i

Inter-VLAN Communication on a Multilayer Switch Through a Switch Virtual Interface Rather than using an external router to provide inter-VLAN communication, a multilayer switch can perform the same task through the use of a switched virtual interface (SVI).

Removing L2 Switchport Capability of a Switch Port interface 3560Switch(config)#i fastethernet 0/1

Moves to interface configuration mode

no switchport 3560Switch(config-if)#n

Creates a Layer 3 port on the switch NOTE: The no switchport command can be used on physical ports only.

Inter-VLAN Communication on a Multilayer Switch Through a Switch Virtual…

47

Configuring Inter-VLAN Communication interface vlan 1 3560Switch(config)#i

Creates a virtual interface for VLAN 1 and enters interface configuration mode

ip address 3550Switch(config-if)#i 172.16.1.1 255.255.255.0

Assigns IP address and netmask

no shutdown 3550Switch(config-if)#n

Enables the interface

interface vlan 10 3550Switch(config)#i

Creates a virtual interface for VLAN 10 and enters interface configuration mode

ip address 3550Switch(config-if)#i 172.16.10.1 255.255.255.0

Assigns IP address and netmask

no shutdown 3550Switch(config-if)#n

Enables the interface

interface vlan 20 3550Switch(config)#i

Creates a virtual interface for VLAN 20 and enters interface configuration mode

ip address 3550Switch(config-if)#i 172.16.20.1 255.255.255.0

Assigns IP address and netmask

no shutdown 3550Switch(config-if)#n

Enables the interface

exit 3550Switch(config-if)#e

Returns to global configuration mode

ip routing 3550Switch(config)#i

Enables routing on the switch

NOTE: The subnets of the VLANs are directly connected to the switch. Routing between these subnets does not require a dynamic routing protocol. If the switch is to be connected to a router and remote communication is desired, a routing protocol must be enabled and networks advertised: router eigrp 1 3560Switch(config)#r network 172.16.0.0 3560Switch(config-router)#n exit 3560Switch(config-router)#e 3560Switch(config)#

48

Configuration Example: Inter-VLAN Communication

Configuration Example: Inter-VLAN Communication Figure 4-1 shows the network topology for the configuration that follows, which shows how to configure inter-VLAN communication using commands covered in this chapter. Some commands used in this configuration are from previous chapters. Figure 4-1

Network Topology for Inter-VLAN Communication Configuration Lo 0 198.133.219.1/24

Internet ISP s 0/0 DCE 192.31.7.5/30 s 0/0 192.31.7.6/30

CORP

fa 0/1 172.31.1.5/30

IEEE 802.1Q Trunk

fa 0/24 172.31.1.6/30 VLAN 1(Native)-172.16.1.1/24 VLAN 10-172.16.10.1/24 VLAN 20-172.16.20.1/24 VLAN 30-172.16.30.1/24

fa 0/0—no IP address fa 0/0.1—VLAN 1 (Native)-192.168.1.1/24 fa 0/0.10—VLAN 10-192.168.10.1/24 fa 0/0.20—VLAN 20-192.168.20.1/24 fa 0/0.30—VLAN 30-192.168.30.1/24

3560 L3Switch1 Gi0/1 Gi0/1

IEEE 802.1Q Gigabit Trunk 2950

L2Switch1

Native VLAN 1 172.16.1.0/24

Accounting VLAN 10 fa 0/1-4 172.16.10.0/24

Marketing VLAN 20 fa 0/5-8 172.16.20.0/24

WS1

WS2

172.16.10.2/24

172.16.20.2/24

VLAN 1 192.168.1.2/24

fa 0/1 2960

L2Switch2

Native VLAN 1 fa 0/1 172.16.1.0/24

Sales VLAN 10 fa 0/2-4 172.16.10.0/24

Engineering VLAN 20 fa 0/5-8 172.16.20.0/24

Marketing VLAN 30 fa 0/9-12 172.16.30.0/24

WS3

WS4

WS5

192.168.10.10/24

192.168.20.20/24

192.168.30.30/24

Configuration Example: Inter-VLAN Communication

49

ISP Router enable Router>e

Moves to privileged mode

configure terminal Router>#c

Moves to global config mode

hostname ISP Router(config)#h

Sets host name

interface loopback 0 ISP(config)#i

Moves to interface configuration mode

description simulated ISP(config-if)#d address representing remote website

Sets locally significant interface description

ip address 198.133.219.1 ISP(config-if)#i 255.255.255.0

Assigns IP address and netmask

interface serial 0/0 ISP(config-if)#i

Moves to interface configuration mode

description WAN link to ISP(config-if)#d the Corporate Router

Sets locally significant interface description

ip address 192.31.7.5 ISP(config-if)#i 255.255.255.252

Assigns IP address and netmask

clock rate 56000 ISP(config-if)#c

Assigns a clock rate to the interface—DCE cable is plugged into this interface

no shutdown ISP(config-if)#n

Enables the interface

exit ISP(config-if)#e

Returns to global configuration mode

router eigrp 10 ISP(config-if)#r

Creates Enhanced Interior Gateway Routing Protocol (EIGRP) routing process 10

network ISP(config-router)#n 198.133.219.0

Advertises directly connected networks (classful address only)

network 192.31.7.0 ISP(config-router)#n

Advertises directly connected networks (classful address only)

no auto-summary ISP(config-router)#n

Disables auto summarization

exit ISP(config-router)#e

Returns to global configuration mode

exit ISP(config)#e

Returns to privileged mode

copy running-config startup-config ISP#c

Saves the configuration to NVRAM

50

Configuration Example: Inter-VLAN Communication

CORP Router enable Router>e

Moves to privileged mode

configure terminal Router>#c

Moves to global configuration mode

hostname CORP Router(config)#h

Sets host name

no ip domain-lookup CORP(config)#n

Turns off Domain Name System (DNS) resolution to avoid wait time due to DNS lookup of spelling errors

interface serial 0/0 CORP(config)#i

Moves to interface configuration mode

description link to ISP CORP(config-if)#d

Sets locally significant interface description

ip address 192.31.7.6 CORP(config-if)#i 255.255.255.252

Assigns IP address and netmask

no shutdown CORP(config-if)#n

Enables interface

interface fastethernet 0/1 CORP(config)#i

Moves to interface configuration mode

description link to 3560 CORP(config-if)#d Switch

Sets locally significant interface description

ip address 172.31.1.5 CORP(config-if)#i 255.255.255.252

Assigns IP address and netmask

no shutdown CORP(config-if)#n

Enables interface

exit CORP(config-if)#e

Returns to global configuration mode

interface fastethernet 0/0 CORP(config)#i

Enters interface configuration mode

duplex full CORP(config-if)#d

Enables full-duplex operation to ensure trunking will take effect between here and L2Switch2

no shutdown CORP(config-if)#n

Enables interface

interface fastethernet CORP(config-if)#i 0/0.1

Creates a virtual subinterface and moves to subinterface configuration mode

description CORP(config-subif)#d Management VLAN 1 – Native VLAN

Sets locally significant interface description

Configuration Example: Inter-VLAN Communication

51

encapsulation dot1q 1 CORP(config-subif)#e native

Assigns VLAN 1 to this subinterface. VLAN 1 will be the native VLAN. This subinterface will use the 802.1Q trunking protocol.

ip address CORP(config-subif)#i 192.168.1.1 255.255.255.0

Assigns IP address and netmask

interface CORP(config-subif)#i fastethernet 0/0.10

Creates a virtual subinterface and moves to subinterface configuration mode

description Sales CORP(config-subif)#d VLAN 10

Sets locally significant interface description

encapsulation dot1q CORP(config-subif)#e 10

Assigns VLAN 10 to this subinterface. This subinterface will use the 802.1Q trunking protocol.

ip address CORP(config-subif)#i 192.168.10.1 255.255.255.0

Assigns IP address and netmask

interface CORP(config-subif)#i fastethernet 0/0.20

Creates a virtual subinterface and moves to subinterface configuration mode

description CORP(config-subif)#d Engineering VLAN 20

Sets locally significant interface description

encapsulation dot1q CORP(config-subif)#e 20

Assigns VLAN 20 to this subinterface. This subinterface will use the 802.1Q trunking protocol.

ip address CORP(config-subif)#i 192.168.20.1 255.255.255.0

Assigns IP address and netmask

interface CORP(config-subif)#i fastethernet 0/0.30

Creates a virtual subinterface and moves to subinterface configuration mode

description CORP(config-subif)#d Marketing VLAN 30

Sets locally significant interface description

encapsulation dot1q CORP(config-subif)#e 30

Assigns VLAN 30 to this subinterface. This subinterface will use the 802.1Q trunking protocol.

ip add 192.168.30.1 CORP(config-subif)#i 255.255.255.0

Assigns IP address and netmask

exit CORP(config-subif)#e

Returns to interface configuration mode

52

Configuration Example: Inter-VLAN Communication

exit CORP(config-if)#e

Returns to global configuration mode

router eigrp 10 CORP(config)#r

Creates EIGRP routing process 10 and moves to router configuration mode

network 192.168.1.0 CORP(config-router)#n

Advertises the 192.168.1.0 network

network CORP(config-router)#n 192.168.10.0

Advertises the 192.168.10.0 network

network CORP(config-router)#n 192.168.20.0

Advertises the 192.168.20.0 network

network CORP(config-router)#n 192.168.30.0

Advertises the 192.168.30.0 network

network 172.31.0.0 CORP(config-router)#n

Advertises the 172.31.0.0 network

network 192.31.7.0 CORP(config-router)#n

Advertises the 192.31.7.0 network

no auto-summary CORP(config-router)#n

Turns off automatic summarization at classful boundary

exit CORP(config-router)#e

Returns to global configuration mode

exit CORP(config)#e

Returns to privileged mode

copy running-config startup-config CORP#c

Saves the configuration in NVRAM

L2Switch2 (Catalyst 2960) enable Switch>e

Moves to privileged mode

configure terminal Switch#c

Moves to global configuration mode

hostname L2Switch2 Switch(config)#h

Sets host name

no ip domain-lookup L2Switch2(config)#n

Turns off DNS resolution

vlan 10 L2Switch2(config)#v

Creates VLAN 10 and enters VLAN-configuration mode

name Sales L2Switch2(config-vlan)#n

Assigns a name to the VLAN

exit L2Switch2(config-vlan)#e

Returns to global configuration mode

Configuration Example: Inter-VLAN Communication

53

vlan 20 L2Switch2(config)#v

Creates VLAN 20 and enters VLAN-configuration mode

name Engineering L2Switch2(config-vlan)#n

Assigns a name to the VLAN

vlan 30 L2Switch2(config-vlan)#v

Creates VLAN 30 and enters VLAN-configuration mode. Note that you do not have to exit back to global configuration mode to execute this command.

name Marketing L2Switch2(config-vlan)#n

Assigns a name to the VLAN

exit L2Switch2(config-vlan)#e

Returns to global configuration mode

interface range L2Switch2(config)#i fastethernet 0/2 – 4

Enables you to set the same configuration parameters on multiple ports at the same time

switchport L2Switch2(config-if-range)#s mode access

Sets ports 2–4 as access ports

switchport L2Switch2(config-if-range)#s access vlan 10

Assigns ports 2–4 to VLAN 10

interface L2Switch2(config-if-range)#i range fastethernet 0/5 – 8

Enables you to set the same configuration parameters on multiple ports at the same time

switchport L2Switch2(config-if-range)#s mode access

Sets ports 5–8 as access ports

switchport L2Switch2(config-if-range)#s access vlan 20

Assigns ports 5–8 to VLAN 20

interface L2Switch2(config-if-range)#i range fastethernet 0/9 - 12

Enables you to set the same configuration parameters on multiple ports at the same time

switchport L2Switch2(config-if-range)#s mode access

Sets ports 9–12 as access ports

switchport L2Switch2(config-if-range)#s access vlan 30

Assigns ports 9–12 to VLAN 30

exit L2Switch2(config-if-range)#e

Returns to global configuration mode

int fastethernet 0/1 L2Switch2(config)#i

Moves to interface configuration mode

description Trunk Link L2Switch2(config)#d to CORP Router

Sets locally significant interface description

54

Configuration Example: Inter-VLAN Communication

switchport mode L2Switch2(config-if)#s trunk

Puts the interface into trunking mode and negotiates to convert the link into a trunk link

exit L2Switch2(config-if)#e

Returns to global configuration mode

interface vlan 1 L2Switch2(config)#i

Creates virtual interface for VLAN 1 and enters interface configuration mode

ip address L2Switch2(config-if)#i 192.168.1.2 255.255.255.0

Assigns IP address and netmask

no shutdown L2Switch2(config-if)#n

Enables interface

exit L2Switch2(config-if)#e

Returns to global configuration mode

ip default-gateway L2Switch2(config)#i 192.168.1.1

Assigns default gateway address

exit L2Switch2(config)#e

Returns to privileged mode

copy running-config startupL2Switch2#c config

Saves the configuration in NVRAM

L3Switch1 (Catalyst 3560) enable Switch>e

Moves to privileged mode

configure terminal Switch#c

Moves to global configuration mode

hostname L3Switch1 Switch(config)#h

Sets Hostname

no ip domain-lookup L3Switch1(config)#n

Turns off DNS queries so that spelling mistakes will not slow you down

vtp mode sever L3Switch1(config)#v

Changes the switch to VTP server mode

vtp domain testdomain L3Switch1(config)#v

Configures the VTP domain name to testdomain

vlan 10 L3Switch1(config)#v

Creates VLAN 10 and enters VLAN-configuration mode

name Accounting L3Switch1(config-vlan)#n

Assigns a name to the VLAN

exit L3Switch1(config-vlan)#e

Returns to global configuration mode

Configuration Example: Inter-VLAN Communication

55

vlan 20 L3Switch1(config)#v

Creates VLAN 20 and enters VLAN-configuration mode

name Marketing L3Switch1(config-vlan)#n

Assigns a name to the VLAN

exit L3Switch1(config-vlan)#e

Returns to global configuration mode

interface L3Switch1(config)#i gigabitethernet 0/1

Moves to interface configuration mode

switchport trunk L3Switch1(config-if)#s encapsulation dot1q

Specifies 802.1Q encapsulation on the trunk link

switchport mode L3Switch1(config-if)#s trunk

Puts the interface into trunking mode and negotiates to convert the link into a trunk link

exit L3Switch1(config-if)#e

Returns to global configuration mode

ip routing L3Switch1(config)#i

Enables IP routing on this device

interface vlan 1 L3Switch1(config)#i

Creates virtual interface for VLAN 1 and enters interface configuration mode

ip address L3Switch1(config-if)#i 172.16.1.1 255.255.255.0

Assigns IP address and netmask

no shutdown L3Switch1(config-if)#n

Enables interface

interface vlan 10 L3Switch1(config-if)#i

Creates virtual interface for VLAN 10 and enters interface configuration mode

ip address L3Switch1(config-if)#i 172.16.10.1 255.255.255.0

Assigns IP address and mask

no shutdown L3Switch1(config-if)#n

Enables interface

interface vlan 20 L3Switch1(config-if)#i

Creates virtual interface for VLAN 20 and enters interface configuration mode

ip address L3Switch1(config-if)#i 172.16.20.1 255.255.255.0

Assigns IP address and mask

no shutdown L3Switch1(config-if)#n

Enables interface

exit L3Switch1(config-if)#e

Returns to global configuration mode

56

Configuration Example: Inter-VLAN Communication

interface fastethernet L3Switch1(config)#i 0/24

Enters interface configuration mode

no switchport L3Switch1(config-if)#n

Creates a Layer 3 port on the switch

ip address L3Switch1(config-if)#i 172.31.1.6 255.255.255.252

Assigns IP address and netmask

exit L3Switch1(config-if)#e

Returns to global configuration mode

router eigrp 10 L3Switch1(config)#r

Creates EIGRP routing process 10 and moves to router config mode

network L3Switch1(config-router)#n 172.16.0.0

Advertises the 172.16.0.0 classful network

network L3Switch1(config-router)#n 172.31.0.0

Advertises the 172.31.0.0 classful network

no auto-summary L3Switch1(config-router)#n

Turns off automatic summarization at classful boundary

exit L3Switch1(config-router)#e

Applies changes and returns to global configuration mode

exit L3Switch1(config)#e

Returns to privileged mode

copy running-config startupL3Switch1#c config

Saves configuration in NVRAM

L2Switch1 (Catalyst 2960) enable Switch>e

Moves to privileged mode

configure terminal Switch#c

Moves to global configuration mode

hostname L2Switch1 Switch(config)#h

Sets host name

no ip domain-lookup L2Switch1(config)#n

Turns off DNS queries so that spelling mistakes will not slow you down

vtp domain testdomain L2Switch1(config)#v

Configures the VTP domain name to testdomain

vtp mode client L2Switch1(config)#v

Changes the switch to VTP client mode

Configuration Example: Inter-VLAN Communication

57

interface range L2Switch1(config)#i fastethernet 0/1 – 4

Enables you to set the same configuration parameters on multiple ports at the same time

switchport L2Switch1(config-if-range)#s mode access

Sets ports 1–4 as access ports

switchport L2Switch1(config-if-range)#s access vlan 10

Assigns ports 1–4 to VLAN 10

interface L2Switch1(config-if-range)#i range fastethernet 0/5 – 8

Enables you to set the same configuration parameters on multiple ports at the same time

switchport L2Switch1(config-if-range)#s mode access

Sets ports 5–8 as access ports

switchport L2Switch1(config-if-range)#s access vlan 20

Assigns ports 5–8 to VLAN 20

exit L2Switch1(config-if-range)#e

Returns to global configuration mode

interface L2Switch1(config)#i gigabitethernet 0/1

Moves to interface configuration mode

switchport mode L2Switch1(config-if)#s trunk

Puts the interface into trunking mode and negotiates to convert the link into a trunk link

exit L2Switch1(config-if)#e

Returns to global configuration mode

interface vlan 1 L2Switch1(config)#i

Creates virtual interface for VLAN 1 and enters interface configuration mode

ip address L2Switch1(config-if)#i 172.16.1.2 255.255.255.0

Assigns IP address and netmask

no shutdown L2Switch1(config-if)#n

Enables interface

exit L2Switch1(config-if)#e

Returns to global configuration mode

ip default-gateway L2Switch1(config)#i 172.16.1.1

Assigns default gateway address

exit L2Switch1(config)#e

Returns to privileged mode

copy running-config startupL2Switch1#c config

Saves the configuration in NVRAM

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CHAPTER 5

High Availability This chapter provides information and commands concerning the following topics: • Hot Standby Routing Protocol (HSRP) — Configuring HSRP — Verifying HSRP — HSRP optimization options — Debugging HSRP • Virtual Router Redundancy Protocol (VRRP) — Configuring VRRP — Verifying VRRP — Debugging VRRP • Gateway Load Balancing Protocol (GLBP) — Configuring GLBP — Verifying GLBP — Debugging GLBP

Hot Standby Routing Protocol The Hot Standby Router Protocol (HSRP) provides network redundancy for IP networks, ensuring that user traffic immediately and transparently recovers from firsthop failures in network edge devices or access circuits.

Configuring HSRP interface Router(config)#i fastethernet 0/0

Moves to interface configuration mode

ip Router(config-if)#i address 172.16.0.10 255.255.255.0

Assigns IP address and netmask

standby Router(config-if)#s 1 ip 172.16.0.1

Activates HSRP group 1 on the interface and creates a virtual IP address of 172.16.0.1 for use in HSRP NOTE: The group number can be from 0 to 255. The default is 0.

standby Router(config-if)#s 1 priority 120

Assigns a priority value of 120 to standby group 1

60

Hot Standby Routing Protocol

NOTE: The priority value can be from 1 to 255. The default is 100. A higher priority will result in that router being elected the active router. If the priorities of all routers in the group are equal, the router with the highest IP address becomes the active router.

Verifying HSRP show running-config Router#s

Displays what is currently running on the router

show standby Router#s

Displays HSRP information

show standby brief Router#s

Displays a single-line output summary of each standby group

show standby 1 Router#s

Displays HSRP group 1 information

show standby fastethernet 0/0 Router#s

Displays HSRP information for the specified interface

show standby fastethernet 0/0 Router#s brief

Displays a summary of HSRP for the specified interface

show standby fastethernet 0/0 Router#s 1

Displays HSRP group 1 information for the specified interface

HSRP Optimization Options There are options available that make it possible to optimize HSRP operation in the campus network. The next three sections explain three of these options: standby preempt, message timers, and interface tracking.

Preempt interface Router(config)#i fastethernet 0/0

Moves to interface configuration mode

standby 1 Router(config-if)#s preempt

This router will preempt, or take control of, the active router if the local priority is higher than the active router

Hot Standby Routing Protocol

standby 1 Router(config-if)#s preempt delay minimum 180

Causes the local router to postpone taking over as the active router for 180 seconds since that router was last restarted

standby 1 Router(config-if)#s preempt delay reload

Allows for preemption to occur only after a router reloads

no standby Router(config-if)#n 1 preempt delay reload

Disables the preemption delay, but preemption itself is still enabled. Use the no standby x preempt command to eliminate preemption

61

NOTE: If the preempt argument is not configured, the local router assumes control as the active router only if the local router receives information indicating that there is no router currently in the active state.

HSRP Message Timers interface Router(config)#i fastethernet 0/0

Moves to interface config mode

standby 1 Router(config-if)#s timers 5 15

Sets the hello timer to 5 seconds and sets the hold timer to 15 seconds NOTE: The hold timer is normally set to be greater than or equal to 3 times the hello timer. NOTE: The hello timer can be from 1 to 254; the default is 3. The hold timer can be from 1 to 255; the default is 10. The default unit of time is seconds.

standby 1 Router(config-if)#s timers msec 200 msec 600

Sets the hello timer to 200 milliseconds and sets the hold timer to 600 milliseconds NOTE: If the msec argument is used, the timers can be an integer from 15 to 999.

62

Virtual Router Redundancy Protocol

Interface Tracking interface Router(config)#i fastethernet 0/0

Moves to interface configuration mode

standby 1 Router(config-if)#s track serial 0/0 25

HSRP will track the availability of interface serial 0/0. If serial 0/0 goes down, the priority of the router in group 1 will be decremented by 25. NOTE: The default value of the track argument is 10. TIP: The track argument does not assign a new priority if the tracked interface goes down. The track argument assigns a value that the priority will be decreased if the tracked interface goes down. Therefore, if you are tracking serial 0/0 with a track value of 25—standby 1 track serial 0/0 25—and serial 0/0 goes down, the priority will be decreased by 25; assuming a default priority of 100, the new priority will now be 75.

Debugging HSRP debug standby Router#d

Displays all HSRP debugging information, including state changes and transmission/ reception of HSRP packets

debug standby errors Router#d

Displays HSRP error messages

debug standby events Router#d

Displays HSRP event messages

debug standby events Router#d terse

Displays all HSRP events except for hellos and advertisements

debug standby events Router#d track

Displays all HSRP tracking events

debug standby packets Router#d

Displays HSRP packet messages

debug standby terse Router#d

Displays all HSRP errors, events, and packets, except for hellos and advertisements

Virtual Router Redundancy Protocol NOTE: HSRP is Cisco proprietary. The Virtual Router Redundancy Protocol (VRRP) is an IEEE standard.

Virtual Router Redundancy Protocol

63

VRRP is an election protocol that dynamically assigns responsibility for one or more virtual routers to the VRRP routers on a LAN, allowing several routers on a multiaccess link to use the same virtual IP address. A VRRP router is configured to run VRRP in conjunction with one or more other routers attached.

Configuring VRRP interface Router(config)#i fastethernet 0/0

Moves to interface config mode

ip Router(config-if)#i address 172.16.100.5 255.255.255.0

Assigns IP address and netmask

vrrp 10 Router(config-if)#v ip 172.16.100.1

Enables VRRP for group 10 on this interface with a virtual address of 172.16.100.1. The group number can be from 1 to 255.

vrrp 10 Router(config-if)#v description Engineering Group

Assigns a text description to the group

vrrp 10 Router(config-if)#v priority 110

Sets the priority level for this router. The range is from 1 to 254. The default is 100.

vrrp 10 Router(config-if)#v preempt

This router will preempt, or take over, as the virtual router master for group 10 if it has a higher priority than the current virtual router master

vrrp 10 Router(config-if)#v preempt delay minimum 60

This router will preempt, but only after a delay of 60 seconds NOTE: The default delay period is 0 seconds.

vrrp 10 Router(config-if)#v timers advertise 15

Configures the interval between successful advertisements by the virtual router master NOTE: The default interval value is 1 second. NOTE: All routers in a VRRP group must use the same timer values. If routers have different timer values set, the VRRP group will not communicate with each other. NOTE: The range of the advertisement timer is 1 to 255 seconds. If you use the msec argument, you change the timer to measure in milliseconds. The range in milliseconds is 50 to 999.

64

Virtual Router Redundancy Protocol

vrrp 10 Router(config-if)#v timers learn

Configures the router, when acting as a virtual router backup, to learn the advertisement interval used by the virtual router master

vrrp 10 Router(config-if)#v shutdown

Disables VRRP on the interface, but configuration is still retained

no vrrp Router(config-if)#n 10 shutdown

Reenables the VRRP group using the previous configuration

Verifying VRRP show running-config Router#s

Displays contents of dynamic RAM

show vrrp Router#s

Displays VRRP information

show vrrp brief Router#s

Displays a brief status of all VRRP groups

show vrrp 10 Router#s

Displays detailed information about VRRP group 10

show vrrp interface Router#s fastethernet 0/0

Displays information about VRRP as enabled on interface fastethernet 0/0

show vrrp interface Router#s fastethernet 0/0 brief

Displays a brief summary about VRRP on interface fastethernet 0/0

Debugging VRRP debug vrrp all Router#d

Displays all VRRP messages

debug vrrp error Router#d

Displays all VRRP error messages

debug vrrp events Router#d

Displays all VRRP event messages

debug vrrp packets Router#d

Displays messages about packets sent and received

debug vrrp state Router#d

Displays messages about state transitions

Gateway Load Balancing Protocol

65

Gateway Load Balancing Protocol Gateway Load Balancing Protocol (GLBP) protects data traffic from a failed router or circuit, like HSRP and VRRP, while allowing packet load sharing between a group of redundant routers.

Configuring GLBP interface fastethernet Router(config)#i 0/0

Moves to interface config mode

ip address Router(config-if)#i 172.16.100.5 255.255.255.0

Assigns IP address and netmask

glbp 10 ip Router(config-if)#g 172.16.100.1

Enables GLBP for group 10 on this interface with a virtual address of 172.16.100.1. The range of group numbers is from 0 to 1023.

glbp 10 preempt Router(config-if)#g

Configures the router to preempt, or take over, as the active virtual gateway (AVG) for group 10 if this router has a higher priority than the current AVG

glbp 10 preempt Router(config-if)#g delay minimum 60

Configures the router to preempt, or take over, as AVG for group 10 if this router has a higher priority than the current active virtual forwarder (AVF) after a delay of 60 seconds

glbp 10 forwarder Router(config-if)#g preempt

Configures the router to preempt, or take over, as AVF for group 10 if this router has a higher priority than the current AVF. This command is enabled by default with a delay of 30 seconds.

glbp 10 forwarder Router(config-if)#g preempt delay minimum 60

Configures the router to preempt, or take over, as AVF for group 10 if this router has a higher priority than the current AVF after a delay of 60 seconds

66

Gateway Load Balancing Protocol

NOTE: Members of a GLBP group elect one gateway to be the AVG for that group. Other group members provide backup for the AVG in the event that the AVG becomes unavailable. The AVG assigns a virtual MAC address to each member of the GLBP group. Each gateway assumes responsibility for forwarding packets sent to the virtual MAC address assigned to it by the AVG. These gateways are known as AVFs for their virtual MAC address. Virtual forwarder redundancy is similar to virtual gateway redundancy with an AVF. If the AVF fails, one of the secondary virtual forwarders in the listen state assumes responsibility for the virtual MAC address. glbp 10 priority 150 Router(config-if)#g

Sets the priority level of the router NOTE: The range of the priority argument is 1 to 255. The default priority of GLBP is 100. A higher priority number is preferred.

glbp 10 timers 5 15 Router(config-if)#g

Configures the hello timer to be set to 5 seconds and the hold timer to be 15 seconds

glbp 10 timers msec Router(config-if)#g 20200 msec 60600

Configures the hello timer to be 20,200 milliseconds and the hold timer to be 60,600 milliseconds. NOTE: The default hello timer is 3 seconds. The range of the hello timer interval is 1 to 60 seconds. If the msec argument is used, the timer will be measured in milliseconds, with a range of 50 to 60000.

Gateway Load Balancing Protocol

67

NOTE: The default hold timer is 10 seconds. The range of the hold timer is 19 to 180 seconds. If the msec argument is used, the timer will be measured in milliseconds, with a range of 18020 to 180000. The hello timer measures the interval between successive hello packets sent by the AVG in a GLBP group. The holdtime argument specifies the interval before the virtual gateway and the virtual forwarder information in the hello packet is considered invalid. It is recommended that unless you are extremely familiar with your network design and with the mechanisms of GLBP that you do not change the timers. To reset the timers back to their default values, use the no glbp x timers command, where x is the GLBP group number. glbp 10 loadRouter(config-if)#g balancing host-dependent

Specifies that GLBP will load balance using the host-dependent method

glbp 10 loadRouter(config-if)#g balancing weighted

Specifies that GLBP will load balance using the weighted method

glbp 10 weighting 80 Router(config-if)#g

Assigns a maximum weighting value for this interface for load-balancing purposes. The value can be from 1 to 254.

glbp 10 load Router(config-if)#g balancing round robin

Specifies that GLBP will load balance using the round-robin method

NOTE:

There are three different types of load balancing in GLBP:

• Host-dependent uses the MAC address of a host to determine which VF MAC address the host is directed toward. This is used with stateful Network Address Translation (NAT) because NAT requires each host to be returned to the same virtual MAC address each time it sends an ARP request for the virtual IP address. It is not recommended for situations where there are a small number of end hosts (fewer than 20).

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Gateway Load Balancing Protocol

• Weighted allows for GLBP to place a weight on each device when calculating the amount of load sharing. For example, if there are two routers in the group, and router A has twice the forwarding capacity of router B, the weighting value should be configured to be double the amount of router B. To assign a weighting value, use the glbp x weighting y interface configuration command, where x is the GLBP group number, and y is the weighting value, a number from 1 to 254. • Round-robin load balancing occurs when each VF MAC address is used sequentially in ARP replies for the virtual IP address. Round robin is suitable for any number of end hosts. If no load balancing is used with GLBP, GLBP will operate in an identical manner to HSRP, where the AVG will only respond to ARP requests with its own VF MAC address, and all traffic will be directed to the AVG.

Verifying GLBP show running-config Router#s

Displays contents of dynamic RAM

show glbp Router#s

Displays GLBP information

show glbp brief Router#s

Displays a brief status of all GLBP groups

show glbp 10 Router#s

Displays information about GLBP group 10

show glbp fastethernet 0/0 Router#s

Displays GLBP information on interface fastethernet 0/0

show glbp fastethernet 0/0 10 Router#s

Displays GLBP group 10 information on interface fastethernet 0/0

Debugging GLBP debug condition glbp Router#d

Displays GLBP condition messages

debug glbp errors Router#d

Displays all GLBP error messages

debug glbp events Router#d

Displays all GLBP event messages

debug glbp packets Router#d

Displays messages about packets sent and received

debug glbp terse Router#d

Displays a limited range of debugging messages

Configuration Example: HSRP

69

Configuration Example: HSRP Figure 5-1 shows the network topology for the configuration that follows, which shows how to configure HSRP using the commands covered in this chapter. Note that only the commands specific to HSRP are shown in this example. Figure 5-1

Network Topology for HSRP Configuration Example

WS1

172.16.16.1/24

WS2

172.16.16.2/24

WS3

172.16.16.3/24

Active Router Priority 105 Preempt is on fa 0/0 172.16.16.5/24

s 0/0 198.133.219.1/30 Virtual IP R1 172.16.16.254/24 s 0/0 DCE 198.133.219.2/30 Fa0/0 is tracking serial 0/0 R3 Fa0/0 is tracking serial 0/1 s 0/0 DCE Virtual IP 198.133.219.6/30 172.16.16.254/24 s 0/0 198.133.219.5/30 R2 fa 0/0 172.16.16.6/24 Standby Router Priority 100 Preempt is on

S1

S2

Router 1 enable Router>e

Moves to privileged mode

configure terminal Router#c

Moves to global configuration mode

hostname R1 Router(config)#h

Sets router name to R1

interface fastethernet 0/0 R1(config)#i

Moves to interface config mode

ip address 172.16.16.5 R1(config-if)#i 255.255.255.0

Assigns IP address and netmask

standby 1 ip R1(config-if)#s 172.16.16.254

Activates HSRP group 1 on the interface and creates a virtual IP address of 172.16.6.254

standby 1 priority 105 R1(config-if)#s

Assigns a priority value of 105 to standby group 1

standby 1 preempt R1(config-if)#s

This router will preempt, or take control of, the active router if the local priority is higher than the active router

70

Configuration Example: HSRP

standby 1 track serial R1(config-if)#s 0/0

HSRP will track the availability of interface serial 0/0. If serial 0/0 goes down, the router priority will be decremented by the default 10.

no shutdown R1(config-if)#n

Enables the interface

interface serial 0/0 R1(config-if)#i

Moves to interface config mode

ip address R1(config-if)#i 198.133.219.1 255.255.255.252

Assigns IP address and netmask

no shutdown R1(config-if)#n

Enables the interface

exit R1(config-if)#e

Returns to global config mode

exit R1(config)#e

Returns to privileged mode

copy running-config startup-config R1#c

Saves the configuration to NVRAM

Router 2 enable Router>e

Moves to privileged mode

configure terminal Router#c

Moves to global config mode

hostname R2 Router(config)#h

Sets router name to R2

interface fastethernet 0/0 R2(config)#i

Moves to interface config mode

ip address 172.16.16.6 R2(config-if)#i 255.255.255.0

Assigns IP address and netmask

standby 1 ip R2(config-if)#s 171.16.16.254

Activates HSRP group 1 on the interface and creates a virtual IP address of 172.16.6.254

standby 1 priority 100 R2(config-if)#s

Assigns a priority value of 100 to standby group 1

standby 1 preempt R2(config-if)#s

This router will preempt, or take control of, the active router if the local priority is higher than the active router

standby 1 track serial R2(config-if)#s 0/1

HSRP will track the availability of interface serial 0/1. If S0/1 goes down, the router priority will be decremented by the default 10.

Configuration Example: GLBP

no shutdown R2(config-if)#n

Enables the interface

interface serial 0/1 R2(config-if)#i

Moves to interface config mode

ip address R2(config-if)#i 198.133.219.5 255.255.255.252

Assigns IP address and netmask

no shutdown R2(config-if)#n

Enables the interface

exit R2(config-if)#e

Returns to global config mode

exit R2(config)#e

Returns to privileged mode

copy running-config startup-config R2#c

Saves the configuration to NVRAM

71

Configuration Example: GLBP Figure 5-2 shows the network topology for the configuration that follows, which shows how to configure GLBP using commands covered in this chapter. Note that only the commands specific to GLBP are shown in this example. Figure 5-2

Network Topology for GLBP Configuration Example

WS1 Default Gateway: 172.16.16.254 Gateway MAC: 0007:b400:0101 Default Gateway: 172.16.16.254 Gateway MAC: 0007:b400:0102 WS2

Active Virtual Router 1 Active Virtual Forwarder 1.1 Fa 0/0 172.16.16.5/24 GLBP Priority 250 Virtual IP R1 172.16.16.254/24 Virtual MAC 0007.b400.0101 GLBP Group 10

WAN

Virtual MAC 0007.b400.0102 GLBP Priority 100 R2 Fa 0/0 172.16.16.6/24 Active Virtual Forwarder 1.2

R1 is the AVG for a GLBP group and is responsible for the virtual IP address 10.21.8.10. R1 is also an AVF for the virtual MAC address 0007.b400.0101. R1 is a member of the same GLBP group and is designated as the AVF for the virtual MAC address 0007.b400.0102.

72

Configuration Example: GLBP

WS1 has a default gateway IP address of 10.21.8.10 and a gateway MAC address of 0007.b400.0101. WS2 shares the same default gateway IP address but receives the gateway MAC address 0007.b400.0102 because R2 is sharing the traffic load with R1.

Router 1 enable Router>e

Moves to privileged mode

configure terminal Router#c

Moves to global config mode

hostname R1 Router(config)#h

Assigns router name

interface fastethernet R1(config)#i 0/0

Moves to interface config mode

ip address R1(config-if)#i 172.16.16.5 255.255.255.0

Assigns IP address and netmask

glbp 10 ip R1(config-if)#g 172.16.16.254

Enables GLBP for group 10 on this interface with a virtual address of 172.16.16.254

glbp 10 preempt R1(config-if)#g

Configures the router to preempt, or take over, as AVG for group 10 if this router has a higher priority than the current AVG

glbp 10 priority R1(config-if)#g 250

Sets the priority level of the router

glbp 10 timers 5 18 R1(config-if)#g

Configures the hello timer to be set to 5 seconds and the hold timer to be 18 seconds

glbp 10 loadR1(config-if)#g balancing host-dependent

Specifies that GLBP will load balance using the host-dependent method

no shutdown R1(config-if)#n

Enables the interface

exit R1(config-if)#e

Returns to global config mode

exit R1(config)#e

Returns to privileged mode

copy running-config startupR1#c config

Saves the configuration to NVRAM

Configuration Example: GLBP

73

Router 2 enable Router>e

Moves to privileged mode

configure terminal Router#c

Moves to global config mode

hostname R2 Router(config)#h

Assigns router name

interface fastethernet R2(config)#i 0/0

Moves to interface config mode

ip address R2(config-if)#i 172.16.16.6 255.255.255.0

Assigns IP address and netmask

glpb 10 ip R2(config-if)#g 172.16.16.254

Enables GLBP for group 10 on this interface with a virtual address of 172.16.16.254

glbp 10 preempt R2(config-if)#g

Configures the router to preempt, or take over, as AVG for group 10 if this router has a higher priority than the current AVG

glbp 10 priority R2(config-if)#g 100

Sets the priority level of the router. The default setting is 100.

glbp 10 timers 5 18 R2(config-if)#g

Configures the hello timer to be set to 5 seconds and the hold timer to be 18 seconds

glbp 10 loadR1(config-if)#g balancing host-dependent

Specifies that GLBP will load balance using the host-dependent method

no shutdown R2(config-if)#n

Enables the interface

exit R2(config-if)#e

Returns to global config mode

exit R2(config)#e

Returns to privileged mode

copy running-config startupR2#c config

Saves the configuration to NVRAM

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CHAPTER 6

Wireless Client Access This chapter provides information and commands concerning the following topics: • Configuration Example: 4402 WLAN Controller Using the Configuration Wizard—Covers the tasks and command-line interface (CLI) commands to — Assign a host name to the wireless LAN controller (WLC) — Enable Telnet access to the WLC — Enable HTTP access to the WLC — Set a timeout of the CLI — Save a configuration — Verify the configuration • Configuration Example: 4402 WLAN Controller Using the Web Interface— Covers the same tasks as listed above in the CLI, but with the graphical user interface (GUI) • Configuration Example: Configuring a 3560 Switch to Support WLANs and APs—Covers how to configure a 3560 switch to support wireless LANs (WLAN) and access points (AP) • Configuration Example: Configuring a Wireless Client—Covers how to configure a Cisco Aironet wireless client adapter

Configuration Example: 4402 WLAN Controller Using the Configuration Wizard NOTE: In the Wireless LAN Controller (WLC) Configuration Wizard, all available options appear in brackets after each parameter. The default value appears in all uppercase letters. Commands are case sensitive.

76

Configuration Example: 4402 WLAN Controller Using the Configuration Wizard

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S/N: XXXXXXXXXXX

Net: PHY DEVICE

: Found Intel LXT971A PHY at 0x01

FEC ETHERNET IDE:

Bus 0: OK

Device 0: Model: STI Flash 7.4.0 Firm: 01.25.06 Ser#: XXXXXXXXXXX Type: Removable Hard Disk Capacity: 245.0 MB = 0.2 GB (501760 x 512) Device 1: not available Booting Primary Image... Press now for additional boot options...

***** External Console Active *****

Select 1 to continue to boot the primary image—this is the default choice Select 2 to boot the backup image (image used before the last software upgrade) Select 3 for manual upgrade of image files

Boot Options

Please choose an option from below:

1. Run primary image (version 4.0.179.8) (active) 2. Run backup image (version 4.0.179.8) 3. Manually update images 4. Change active boot image 5. Clear Configuration

Please enter your choice: 1

Detecting Hardware . . .

Select 4 to set the backup image as the primary image Select 5 to set the configuration back to factory default and start the CLI Setup Wizard using the current software

Configuration Example: 4402 WLAN Controller Using the Configuration Wizard

77

NOTE: Option 3 is for recovery only. Do not select this option unless you have the required files and are instructed to do so by the Cisco Technical Assistance Center (TAC).

Welcome to the Cisco Wizard Configuration Tool Use the '-' character to backup

Press the hyphen key if you ever need to return to the previous command line

System Name [Cisco_xx:xx:xx]:

Enters the system name for the controller. Length is up to 32 ASCII characters. If no name is entered, a default of Cisco Controller is used.

Enter Administrative User Name (24 characters max): cisco

Assigns the administrative username and password. The default username and password are admin and admin.

Enter Administrative Password (24 characters max): password

Service Interface IP Address Configuration DHCP [none][DHCP]:D

Enter DHCP if you want the controller’s serviceport interface to obtain its IP address from a DHCP server. Enter none if you want to set one statically or if you don’t want to use the service port.

78

Configuration Example: 4402 WLAN Controller Using the Configuration Wizard

NOTE: The service-port interface controls communications through the service port. Its IP address must be on a different subnet from the management and APmanager interfaces. This enables you to manage the controller directly or through a dedicated management network to ensure service access during network downtime. NOTE: If you do not want to use the service port, enter 0.0.0.0 for the IP address and subnet mask. If you want to statically assign an address and mask, do so on the next two lines when prompted. Enable Link Aggregation (LAG) [yes][NO]:

Enables link aggregation, if desired

Management Interface IP Address: 172.16.1.100

Assigns IP address, netmask, default router IP address, optional VLAN identifier of the management interface, and port number of the management interface

Management Interface Netmask: 255.255.255.0 Management Interface Default Router: 172.16.1.1 Management Interface VLAN Identifier (0 = untagged): 0 Management Interface Port Num [1 to 2]: 1 Management Interface DHCP Server IP Address: 172.16.1.1

Assigns the IP address of the DHCP server that will assign addresses to the management interface and service-port interface NOTE: The VLAN identifier should be set to match the switch interface configuration.

Configuration Example: 4402 WLAN Controller Using the Configuration Wizard

79

NOTE: The management interface is the default interface for in-band management of the controller and connectivity to enterprise services such as an authentication, authorization, and accounting (AAA) server. AP Transport Mode [layer2][LAYER3]:

Sets AP transport layer

AP Manager Interface IP Address: 172.16.100.100

Assigns IP address, netmask, default router IP address, optional VLAN identifier, and port number of the AP manager interface

AP Manager Interface Netmask: 255.255.255.0 AP Manager Interface Default Router: 172.16.100.1 AP Manager Interface VLAN Identifier (0 = untagged): 100 AP Manager Interface Port Num [1 to 2]: 1 AP Manager Interface DHCP Server (172.16.1.1): 172.16.100.1

Assigns the IP address of the DHCP server that will assign addresses to the APs NOTE: The AP manager interface is used for Layer 3 communication between the controller and the lightweight APs. It must have a unique IP address and is usually configured as the same VLAN or IP subnet as the management interface, but is not required to be. NOTE: If the AP manager interface is on the same subnet as the management interface, the same DHCP server is used for the AP manager interface and the management interface.

80

Configuration Example: 4402 WLAN Controller Using the Configuration Wizard

Virtual Gateway IP Address: 1.1.1.1

Assigns an IP address to the controller's virtual interface. NOTE: Because the virtual gateway will not be routed, use a fictitious, unassigned IP address, such as 1.1.1.1. All controllers within a mobility group must be configured with the same virtual interface IP address.

Mobility/RF Group Name: bcmsn

Assigns the name of the mobility group/RF group to which this controller belongs

Network Name (SSID): bcmsn

Assigns the service set identifier (SSID)

Allow Static IP Addresses [YES][no]:

Enter yes (or press the ® key) if you want to allow clients to assign their own IP addresses. Enter no if you want to force clients to use IP addresses from a DHCP server.

Configure a RADIUS Server now? [YES][no]: no

Enter yes if you want to configure a RADIUS server now. Enter no if you do not want to do so at this time.

Warning! The default WLAN security policy requires a RADIUS server. Please see documentation for more details. Enter Country Code (enter 'help' for a list of countries) [US]: US

Assigns the country code

Enable 802.11b Network [YES][no]:

Enter yes (or press the ® key) to enable each of the 802.11b, a, or g lightweight AP networks. Enter no to disable.

Enable 802.11a Network [YES][no]: Enable 802.11g Network [YES][no]:

Configuration Example: 4402 WLAN Controller Using the Configuration Wizard

Enable Auto-RF [YES][no]:

81

Enter yes to enable or no to disable the Radio Resource Management (RRM) auto-RF feature NOTE: The auto-RF feature enables the controller to automatically form an RF group with other controllers.

Configuration saved! Resetting system with new configuration...

Controller saves configuration and then automatically reboots the controller NOTE: This is the end of the wizard. From here on are examples of commands used to continue with the configuration and verification of the controller.

(Cisco Controller)

Enter User Name (or 'Recover-Config' this onetime only to reset configuration to factory defaults)

Enter your username and password to log in to the controller

User: cisco

Password:******** config prompt (Cisco Controller) >c WLAN_Controller

Changes the controller prompt to WLAN_Controller. The length of this prompt is 31 alphanumeric characters.

82

Configuration Example: 4402 WLAN Controller Using the Configuration Wizard

config network telnet enable (WLAN_Controller) >c

Enables Telnet access to the WLAN controller. By default, controllers block Telnet connections.

config network webmode enable (WLAN_Controller) >c

Enables HTTP access to the WLAN controller NOTE: HTTPS access is enabled by default; unsecured HTTP is not

config serial timeout 3 (WLAN_Controller) >c

Sets automatic logout of the CLI to 3 minutes NOTE: The default timeout for the CLI is 0 minutes. The range of the config serial timeout command is 0 to 160, measured in minutes, where 0 represents never logging out.

save config (WLAN_Controller) >s

Saves the configuration

Are you sure you want to save? (y/n) y

Configuration Saved!

show interface summary (WLAN_Controller) >s

Displays current interface configuration

show run-config (WLAN_Controller) >s

Displays current configuration

show ap summary (WLAN_Controller) >s

Displays a summary of all Cisco 1000 series lightweight APs attached to the controller

show wlan summary (WLAN_Controller) >s

Displays a summary of the WLANs

(WLAN_Controller) > show port summary

Displays the status of the controller's distribution system ports

Configuration Example: 4402 WLAN Controller Using the Configuration Wizard

83

After configuration is complete, you can open up a web browser and connect to the device. Figure 6-1 shows the GUI login screen. Using the preceding configuration as a guide, you would connect to 172.16.1.100. If you are connecting to an unconfigured controller, you would use the address 192.168.1.1. Figure 6-1

GUI Login Screen

Figure 6-2 shows the Login screen once the Login button has been pressed. Figure 6-2

GUI Login Screen After the Login Button Has Been Pressed

84

Configuration Example: 4402 WLAN Controller Using the Web Interface

Figure 6-3 shows the main page after a successful login. Figure 6-3

Main Page

Configuration Example: 4402 WLAN Controller Using the Web Interface NOTE: The Cisco 4400 series WLAN controller supports the initial configuration via a web browser through the service port. The default address of the unconfigured controller is 192.168.1.1. The default username and password are both admin. Cisco recommends using Internet Explorer 6.0 with Service Pack 1 (SP1) or later with full switch web interface functionality. There are known issues with Opera, Mozilla, and Netscape.

Refer back to Figure 6-1 and Figure 6-2 for the GUI Login screen. If you use the default address of 192.168.1.1 and the default username/password combination of admin/admin, the GUI Configuration Wizard will appear. Figure 6-4 shows the first screen of the GUI Configuration Wizard.

Configuration Example: 4402 WLAN Controller Using the Web Interface

Figure 6-4

85

First Screen of the GUI Configuration Wizard

Figure 6-5 shows the second screen of the GUI Configuration Wizard. This is where you configure the IP address and netmask of the service interface and enable DHCP, if desired. Figure 6-5

Service Interface Configuration of the GUI Configuration Wizard

86

Configuration Example: 4402 WLAN Controller Using the Web Interface

Figure 6-6 shows the third screen of the GUI Configuration Wizard. This is where you assign the IP address, netmask, default router IP address, optional VLAN identifier of the management interface, and port number of the management interface. You also configure the IP address of the DHCP server that will assign addresses to the APs. Note that if you leave the VLAN identifier as zero, it means the interface is untagged. Figure 6-6

Management Interface Configuration Screen of the GUI Configuration Wizard

Figure 6-7 shows the fourth screen of the GUI Configuration Wizard. This is where you set the AP transport layer mode along with the RF mobility domain name and the country code. Note that the screen scrolls down to list more country codes Figure 6-8 shows the fifth screen of the GUI Configuration Wizard. This is where you assign the IP address, netmask, default router IP address, optional VLAN identifier, and port number of the AP Manager Interface. You also assign the address of the DHCP server. If the AP manager interface is on the same subnet as the management interface, the same DHCP server is used for the AP manager interface and the management interface.

Configuration Example: 4402 WLAN Controller Using the Web Interface

87

Figure 6-7

Miscellaneous Configuration of the GUI Configuration Wizard

Figure 6-8

AP Manager Interface Configuration Screen of the GUI Configuration Wizard

88

Configuration Example: 4402 WLAN Controller Using the Web Interface

Figure 6-9 shows the sixth screen of the GUI Configuration Wizard. This is where you assign the IP address of the virtual interface. Because the virtual gateway will not be routed, use a fictitious, unassigned IP address, such as 1.1.1.1. All controllers within a mobility group must be configured with the same virtual interface IP address. Figure 6-9

Virtual Interface Configuration Screen of the GUI Configuration Wizard

Figure 6-10 shows the seventh screen of the GUI Configuration Wizard. This is where you configure the WLAN SSID, along with general policies and security policies. You also set the 802.1x parameters here. Figure 6-11 shows the eighth screen of the GUI Configuration Wizard. This is where you configure your RADIUS server. In this example, no RADIUS server was wanted, so this screen was left to the default settings.

Configuration Example: 4402 WLAN Controller Using the Web Interface

Figure 6-10

WLAN Policy Configuration Screen of the GUI Configuration Wizard

Figure 6-11

RADIUS Server Configuration Screen of the GUI Configuration Wizard

89

90

Configuration Example: 4402 WLAN Controller Using the Web Interface

Figure 6-12 shows the ninth screen of the GUI Configuration Wizard. This is where you enable the network status of your wireless technologies—802.11a/b/g and Auto-RF. Figure 6-12

802.11 Configuration Screen of the GUI Configuration Wizard

Figure 6-13 shows the tenth screen of the GUI Configuration Wizard. At this point, the configuration is complete. The pop-up will appear after you click the Save and Reboot button. The configuration will save, and the controller will then restart. After the system has been rebooted, HTTP will no longer work. You must use HTTPS. Figure 6-14 shows the Login screen in HTTPS.

Configuration Example: 4402 WLAN Controller Using the Web Interface

91

Figure 6-13

Configuration Wizard Complete Screen of the GUI Configuration Wizard

Figure 6-14

Login Screen in HTTPS

92

Configuration Example: 4402 WLAN Controller Using the Web Interface

To enable HTTP access, choose the Management tab on the top of the page, and then select HTTP on the left side of the screen, as illustrated in Figure 6-15. Choose the Enabled option for HTTP Access. Note that in Figure 6-15, HTTP has not been enabled yet, but HTTPS has. Figure 6-15

Enabling HTTP Access

To change the controller name, choose the Management tab on the top of the page, and then select SNMP on the left side of the screen, as illustrated in Figure 6-16. Here you can change the controller name, add a description of the location of the controller, and add the contact information of the controller administrator.

Configuration Example: 4402 WLAN Controller Using the Web Interface

Figure 6-16

Changing Controller Name

Figure 6-17 shows a summary of the menu bar in the GUI of the WLC. Figure 6-17

WLC Web Menu Bar WIRELESS Provides access point configurations, client management, and various RF settings

WLAN Provides WLAN configurations, such as SSIDs and security policies, for all the user groups

MONITOR Provides a view of this controller, its access points, and wireless clients

MANAGEMENT Provides integration into the network, such as IP addressing and SNMP

SECURITY Provides integration into security structure, such as RADIUS connectivity

CONTROLLER Provides controller-wide configurations, such as Layer 2/3 mode, multicast, and mobility settings

COMMANDS Provides administrative options, such as upgrades and backup

93

94

Configuration Example: Configuring a 3560 Switch to Support WLANs and APs

Configuration Example: Configuring a 3560 Switch to Support WLANs and APs Figure 6-18 shows the network topology for the configuration that follows, which shows how to configure a 3560 switch to support WLANs and APs. Figure 6-18

Topology for WLAN/AP Support Configuration on a 3560 Switch

VLAN1: 172.16.1.100/24 VLAN100: 172.16.100.100/24 4402 Wireless LAN Controller

Distribution Switch 3560

FA 0/1

FA 0/12

802.1q Trunk

VLAN1

WS1

FA 0/24 VLAN100

WLAN_Controller

LWAPP LWAP1

enable Switch>e

Moves to privileged mode

configure terminal Switch#c

Moves to global configuration mode

hostname 3560 Switch(config)#h

Sets host name of switch

vlan 1 3560(config)#v

Enters VLAN-configuration mode

name Management 3560(config-vlan)#n

Assigns a name to VLAN 1

exit 3560(config-vlan)#e

Returns to global config mode

vlan 100 3560(config)#v

Creates VLAN 100 and enters VLANconfig mode

name Wireless 3560(config-vlan)#n

Assigns a name to VLAN 100

exit 3560(config-vlan)#e

Returns to global config mode

interface vlan 1 3560(config)#i

Moves to interface configuration mode

ip address 3560(config-if)#i 172.16.1.1 255.255.255.0

Assigns IP address and netmask

Configuration Example: Configuring a 3560 Switch to Support WLANs and APs

95

no shutdown 3560(config-if)#n

Enables the interface

interface vlan 100 3560(config-if)#i

Moves to interface config mode

ip address 3560(config-if)#i 172.16.100.1 255.255.255.0

Assigns IP address and netmask

no shutdown 3560(config-if)#n

Enables the interface

exit 3560(config-if)#e

Returns to global config mode

ip dhcp pool wireless 3560(config)#i

Creates a DHCP pool called wireless and enters DHCP configuration mode

network 3560(config-dhcp)#n 172.16.100.0 255.255.255.0

Defines the range of addresses to be leased

default router 3560(config-dhcp)#d 172.16.100.1

Defines the address of the default router for the client

exit 3560(config-dhcp)#e

Returns to global config mode

interface fastethernet 3560(config)#i 0/1

Moves to interface config mode

description link to 3560(config-if)#d WLAN_Controller

Creates locally significant description

switchport mode 3560(config-if)#s trunk

Makes this interface a trunk port

interface 3560(config-if)#i fastethernet 0/24

Moves to interface config mode for interface fastethernet 0/24

description link to 3560(config-if)#d Access Point

Creates locally significant description

switchport mode 3560(config-if)#s access

Makes this interface an access port

switchport access 3560(config-if)#s vlan 100

Assigns this interface to VLAN 100

spanning-tree 3560(config-if)#s portfast

Enables PortFast on this interface

exit 3560(config-if)#e

Returns to global config mode

exit 3560(config)#e

Returns to privileged mode

copy running-config startup3560#c config

Saves the configuration to NVRAM

96

Configuration Example: Configuring a Wireless Client

Configuration Example: Configuring a Wireless Client Refer back to Figure 6-18, which shows the network topology for the following configuration on how to configure a Cisco Aironet wireless client adapter: Step 1.

Install a Cisco Aironet Wireless Adapter into an open slot on your laptop.

Step 2.

Load the Cisco Aironet Desktop Utility software onto your laptop.

Step 3.

If necessary, reboot your machine, and then run the Aironet Desktop Utility program.

Step 4.

Open the Profiles Management tab and click New (see Figure 6-19).

Figure 6-19

Profile Management Screen

Step 5.

Enter your profile name, client name, and SSID (see Figure 6-20).

Step 6.

Open the Security tab and choose None (see Figure 6-21).

Configuration Example: Configuring a Wireless Client

Figure 6-20

SSID Configuration

Figure 6-21

Security Options

97

98

Configuration Example: Configuring a Wireless Client

Step 7.

Figure 6-22

Step 8.

Open the Advanced tab. Uncheck the 5GHz 54 Mbps, because you are not using 802.11a. Then click OK (see Figure 6-22). Advanced Options

After clicking OK, you are returned to the Profile Management screen. In addition to the default profile, there is a new profile called ccnppod. Select the ccnppod profile and click the Activate button. After clicking the Activate button, the screen will look like Figure 6-23.

Configuration Example: Configuring a Wireless Client

Figure 6-23

Step 9.

Figure 6-24

ccnppod Profile Activated

Click the Current Status tab, and your screen should look similar to Figure 6-24. Current Status of ccnppod Profile

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CHAPTER 7

Minimizing Service Loss and Data Theft This chapter provides information and commands concerning the following topics: • Configuring static MAC addresses • Switch port security • Verifying switch port security • Sticky MAC addresses • Mitigating VLAN hopping: best practices • Configuring private VLANs (PVLAN) • Verifying PVLANs • Configuring protected ports • VLAN access maps • Verifying VLAN access maps • DHCP snooping • Verifying DHCP snooping • Dynamic ARP Inspection (DAI) • Verifying DAI • 802.1x port-based authentication • Cisco Discovery Protocol (CDP) security issues • Configuring the Secure Shell (SSH) protocol • vty access control lists (ACL) • Restricting web interface sessions with ACLs • Disabling unneeded services • Securing end-device access ports

Configuring Static MAC Addresses You can define the forwarding behavior of a switch port by adding a static MAC address to your configuration. This MAC address can be either a unicast or a multicast address, and the entry does not age and is retained when the switch restarts.

102

Switch Port Security

macaddress-table Switch(config)#m static cf23.1943.9a4b vlan 1 interface fastethernet 0/3

Destination MAC address cf23.1943.9a4b is added to the MAC address table. Packets with this address are forwarded out interface fastethernet 0/3. NOTE: Beginning with Cisco IOS Software Release 12.1(11)EA1, the mac address-table static command (no hyphen) replaces the mac-address-table command (with the hyphen). The macaddress-table static command (with the hyphen) will become obsolete in a future release.

mac address-table Switch(config)#m static 1234.5678.90ab vlan 4 interface gigabitethernet 0/1

Destination MAC address 1234.5678.90ab is added to the MAC address table. Packets with this address and forwarded out interface gigabitethernet 0/1.

Switch Port Security interface Switch(config)#i fastethernet 0/1

Moves to interface configuration mode

switchport portSwitch(config-if)#s security

Enables port security on the interface

switchport portSwitch(config-if)#s security maximum 4

Sets a maximum limit of 4 MAC addresses that will be allowed on this port NOTE: The maximum number of secure MAC addresses that you can configure on a switch is set by the maximum number of available MAC addresses allowed in the system.

switchport portSwitch(config-if)#s security mac-address 1234.5678.90ab

Sets a specific secure MAC address 1234.5678.90ab. You can add additional secure MAC addresses up to the maximum value configured.

switchport portSwitch(config-if)#s security violation shutdown

Configures port security to shut down the interface if a security violation occurs

Verifying Switch Port Security

103

NOTE: In shutdown mode, the port is errdisabled, a log entry is made, and manual intervention or errdisable recovery must be used to reenable the interface. switchport portSwitch(config-if)#s security violation restrict

Configures port security to restrict mode if a security violation occurs NOTE: In restrict mode, frames from a nonallowed address are dropped, and a log entry is made. The interface remains operational.

switchport portSwitch(config-if)#s security violation protect

Configures port security to protect mode if a security violation occurs NOTE: In protect mode, frames from a nonallowed address are dropped, but no log entry is made. The interface remains operational.

Verifying Switch Port Security show port-security Switch#s

Displays security information for all interfaces

show port-security Switch#s interface fastethernet 0/5

Displays security information for interface fastethernet 0/5

show port-security address Switch#s

Displays MAC address table security Information

show mac address-table Switch#s

Displays the MAC address table

clear mac address-table Switch#c dynamic

Deletes all dynamic MAC addresses

clear mac address-table Switch#c dynamic address aaaa.bbbb.cccc

Deletes the specified dynamic MAC address

clear mac address-table Switch#c dynamic interface fastethernet 0/5

Deletes all dynamic MAC addresses on interface fastethernet 0/5

clear mac address-table Switch#c dynamic vlan 10

Deletes all dynamic MAC addresses on VLAN 10

104

Sticky MAC Addresses

clear mac address-table Switch#c notification

Clears MAC notification global counters NOTE: Beginning with Cisco IOS Software Release 12.1(11)EA1, the clear mac address-table command (no hyphen) replaces the clear mac-addresstable command (with the hyphen). The clear mac-address-table static command (with the hyphen) will become obsolete in a future release.

Sticky MAC Addresses Sticky MAC addresses are a feature of port security. Sticky MAC addresses limit switch port access to a specific MAC address that can be dynamically learned, as opposed to a network administrator manually associating a MAC addresses with a specific switch port. These addresses are stored in the running configuration file. If this file is saved, the sticky MAC addresses will not have to be relearned when the switch is rebooted, providing a high level of switch port security.

interface Switch(config)#i fastethernet 0/5

Moves to interface config mode

switchport portSwitch(config-if)#s security mac-address sticky

Converts all dynamic port security– learned MAC addresses to sticky secure MAC addresses

switchport portSwitch(config-if)#s security mac-address sticky vlan 10 voice

Converts all dynamic port security– learned MAC addresses to sticky secure MAC addresses on voice VLAN 10 NOTE: The voice keyword is available only if a voice VLAN is first configured on a port and if that port is not the access VLAN.

Configuring Private VLANs

105

Mitigating VLAN Hopping: Best Practices Configure all unused ports as access ports so that trunking cannot be negotiated across those links. Place all unused ports in the shutdown state and associate with a VLAN designed only for unused ports, carrying no user data traffic. When establishing a trunk link, purposefully configure the following: • The native VLAN to be different from any data VLANs • Trunking as on, rather than negotiated • The specific VLAN range to be carried on the trunk

Configuring Private VLANs A problem can potentially exist when an Internet service provider (ISP) has many devices from different customers on a single demilitarized zone (DMZ) segment or VLAN—these devices are not isolated from each other. Some switches can implement private VLANs (PVLAN), which will keep some switch ports shared and some isolated, even though all ports are in the same VLAN. This isolation eliminates the need for a separate VLAN and IP subnet per customer.

NOTE: Private VLANs are implemented on Catalyst 6500/4500/3750/3560 switches.

vtp mode Switch(config)#v transparent

Sets VLAN Trunking Protocol (VTP) mode to transparent

vlan 20 Switch(config)#v

Creates VLAN 20 and moves to VLANconfiguration mode

private-vlan Switch(config-vlan)#p primary

Creates a private, primary VLAN

vlan 101 Switch(config-vlan)#v

Creates VLAN 101 and moves to VLANconfig mode

private-vlan Switch(config-vlan)#p isolated

Creates a private, isolated VLAN for VLAN 101 NOTE: An isolated VLAN can only communicate with promiscuous ports.

exit Switch(config-vlan)#e

Returns to global configuration mode

vlan 102 Switch(config)#v

Creates VLAN 102 and moves to VLANconfig mode

106

Verifying PVLANs

private-vlan Switch(config-vlan)#p community

Creates a private, community VLAN for VLAN 102 NOTE: A community VLAN can communicate with all promiscuous ports and with other ports in the same community.

exit Switch(config-vlan)#e

Returns to global config mode

vlan 103 Switch(config)#v

Creates VLAN 103 and moves to VLANconfig mode

private-vlan Switch(config-vlan)#p community

Creates a private, community VLAN for VLAN 103

vlan 20 Switch(config-vlan)#v

Returns to VLAN-config mode for VLAN 20

private-vlan Switch(config-vlan)#p association 101-103

Associates secondary VLANs 101–103 with primary VLAN 20 NOTE: Only one isolated VLAN can be mapped to a primary VLAN, but more than one community VLAN can be mapped to a primary VLAN.

interface Switch(config)#i fastethernet 0/20

Moves to interface config mode

switchport Switch(config-if)#s mode private-vlan host

Configures the port as a private VLAN host port

switchport Switch(config-if)#s private-vlan host-association 20 101

Associates the port with primary private VLAN 20 and secondary private VLAN 101

Verifying PVLANs show vlan private-vlan Switch#s type

Verifies private VLAN configuration

show interface Switch#s fastethernet 0/20 switchport

Verifies all configuration on fastethernet 0/ 20, including private VLAN associations

VLAN Access Maps

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Configuring Protected Ports NOTE: Although 2960/3560 switches do not support private VLANs, they do support protected ports, which has a similar functionality to PVLANs on a perswitch basis.

interface Switch(config)#i fastethernet 0/17

Moves to interface config mode

switchport Switch(config-if)#s protected

Configures interface to be a protected port NOTE: The use of protected ports ensures that there is no exchange of unicast, broadcast, or multicast traffic between these ports on the switch. Only control traffic will be forwarded. All data traffic passing between protected ports must be forwarded through a Layer 3 device.

exit Switch(config-if)#e

Returns to global config mode

VLAN Access Maps VLAN access maps are the only way to control filtering within a VLAN. VLAN access maps have no direction—if you want to filter traffic in a specific direction, you need to include an access control list (ACL) with specific source or destination addresses. VLAN access maps do not work on the 2960 platform, but they do work on the 3560 and the 6500 platforms.

ip access3560Switch(config)#i list extended test1

Creates a named extended ACL called test1

3560Switch(config-extpermit tcp any any nacl)#p

The first line of an extended ACL will permit any TCP packet from any source to travel to any destination address. Because there is no other line in this ACL, the implicit deny statement that is part of all ACLS will deny any other packet.

3560Switch(config-extexit nacl)#e

Exits named ACL configuration mode and returns to global config mode

108

VLAN Access Maps

vlan access3560Switch(config)#v map drop_TCP

Creates a VLAN access map named drop_TCP and moves into VLAN access map configuration mode. If no sequence number is given at the end of the command, a default number of 10 is assigned.

3560Switch(config-accessmatch ip address test1 map)#m

Defines what needs to occur for this action to continue. In this case, packets filtered out by the named ACL test1 will be acted upon. NOTE: You can match ACLs based on the following: IP ACL number: 1–199 and 1300–2699 IP ACL name IPX ACL number: 800–999 IPX ACL name MAC address ACL name

3560Switch(config-accessaction drop map)#a

Any packet that is filtered out by the ACL test1 will be dropped NOTE: You can configure the following actions: Drop Forward Redirect (works only on a Catalyst 6500)

3560Switch(config-accessexit drop)#e

Exits access map configuration mode and returns to global config mode

vlan filter 3560Switch(config)#v drop_TCP vlan-list 20-30

Applies the VLAN map named drop_TCP to VLANs 20–30 NOTE: The vlan-list argument can refer to a single VLAN (26), a consecutive list (20– 30), or a string of VLAN IDs (12, 22, 32). Spaces around the comma and hyphen are optional.

Configuration Example: VLAN Access Maps

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Verifying VLAN Access Maps show vlan access-map Switch#s

Displays all VLAN access maps

show vlan access-map Switch#s drop_TCP

Displays the VLAN access map named drop_TCP

show vlan filter Switch#s

Displays what filters are applies to all VLANs

show vlan filter accessSwitch#s map drop_TCP

Displays the filter for the specific VLAN access map named drop_TCP

Configuration Example: VLAN Access Maps Figure 7-1 shows the network topology for the configuration that follows, which shows how to configure VLAN access maps using the commands covered in this chapter. Figure 7-1

Network Topology for VLAN Access Map Configuration 3560 WS3

192.168.10.10/24 VLAN 10

Host in 192.168.20.0/24 VLAN 20

WS2

WS1

192.168.10.40/24 VLAN 10

192.168.10.41/24 VLAN 10

The objective of the VLAN access map is to deny all IP traffic from VLAN 20 from reaching the server in VLAN 10. A specific host in VLAN 10 with an IP address of 192.168.10.40/24 is also denied access to the server. All other IP traffic is allowed.

The objective of the VLAN access map is to deny all IP traffic from VLAN 20 from reaching the server in VLAN 10. A specific host in VLAN 10 with an IP address of 192.168.10.40/24 is also denied access to the server. All other IP traffic is allowed. A 3560 switch is used for this example.

110

Configuration Example: VLAN Access Maps

ip access-list 3560(config)#i extended DENY_SERVER_ACL

Creates a named ACL called DENY_SERVER_ACL and moves to named ACL configuration mode

permit ip 3560(config-ext-nacl)#p 192.168.20.0 0.0.0.255 host 192.168.10.10

This line filters out all IP packets from a source address of 192.168.20.x destined for the server at 192.168.10.10

permit ip 3560(config-ext-nacl)#p host 192.168.10.40 host 192.168.10.10

This line filters out all IP packets from a source address of 192.168.10.40 destined for the server at 192.168.10.10

exit 3560(config-ext-nacl)#e

Returns to global config mode

vlan access-map 3560(config)#v DENY_SERVER_MAP 10

Creates a VLAN access map called DENY_SERVER_MAP and moves into VLAN access map config mode. If no sequence number is given at the end of the command, a default number of 10 is assigned.

match ip 3560(config-access-map)#m address DENY_SERVER_ACL

Defines what needs to occur for this action to continue. In this case, packets filtered out by the named ACL DENY_SERVER_ACL will be acted upon.

action 3560(config-access-map)#a drop

Any packet filtered out by the ACL will be dropped

exit 3560(config-access-map)#e

Returns to global config mode

vlan access-map 3560(config)#v DENY_SERVER_MAP 20

Creates line 20 of the VLAN access map called DENY_SERVER_MAP and moves into VLAN access map config mode

action 3560(config-access-map)#a forward

Any packet not filtered out by the ACL in line 10 will be forwarded

exit 3560(config-access-map)#e

Returns to global config mode

vlan filter 3560(config)#v DENY_SERVER_MAP vlan-list 10

Applies the VLAN map to VLAN 10

DHCP Snooping

111

DHCP Snooping DHCP snooping is a DHCP security feature that provides network security by filtering untrusted DHCP messages and by building and maintaining a DHCP snooping binding database, which is also referred to as a DHCP snooping binding table.

ip dhcp snooping Switch(config)#i

Enables DHCP snooping globally NOTE: If you enable DHCP snooping on a switch, the following DHCP relay agent commands are not available until snooping is disabled: ip dhcp relay Switch(config)#i information check ip dhcp relay Switch(config)#i information policy {drop | keep | replace}Switch(config)#ip dhcp relay information trust-all ip dhcp relay Switch(config-if)#i information trusted

If you enter these commands with DHCP snooping enabled, the switch returns an error message. ip dhcp snooping Switch(config)#i vlan 20

Enables DHCP snooping on VLAN 20

ip dhcp snooping Switch(config)#i vlan 10-35

Enables DHCP snooping on VLANs 10–35

ip dhcp snooping Switch(config)#i vlan 20 30

Enables DHCP snooping on VLANs 20–30

ip dhcp snooping Switch(config)#i 10,12,14

Enables DHCP snooping on VLANs 10, 12, and 14

ip dhcp snooping Switch(config)#i information option

Enables DHCP option 82 insertion

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DHCP Snooping

NOTE: DHCP address allocation is usually based on an IP address—either the gateway IP address or the incoming interface IP address. In some networks, you might need additional information to determine which IP address to allocate. By using the “relay agent information option”—option 82—the Cisco IOS relay agent can include additional information about itself when forwarding DHCP packets to a DHCP server. The relay agent will add the circuit identifier suboption and the remote ID suboption to the relay information option and forward this all to the DHCP server. interface Switch(config)#i fasthethernet 0/1

Moves to interface config mode

ip dhcp Switch(config-if)#i snooping trust

Configures the interface as trusted NOTE: There must be at least one trusted interface when working with DHCP snooping. It is usually the port connected to the DHCP server or to uplink ports. By default, all ports are untrusted.

ip dhcp Switch(config-if)#i snooping limit rate 75

Configures the number of DHCP packets per second that an interface can receive NOTE: The range of packets that can be received per second is 1 to 4,294,967,294. The default is no rate configured. TIP: Cisco recommends an untrusted rate limit of no more than 100 packets per second.

ip dhcp Switch(config-if)#i snooping verify mac-address

Configures the switch to verify that the source MAC address in a DHCP packet that is received on an untrusted port matches the client hardware address in the packet

Dynamic ARP Inspection

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Verifying DHCP Snooping show ip dhcp snooping Switch#s

Displays the DHCP snooping configuration for a switch

show ip dhcp snooping Switch#s binding

Displays only the dynamically configured bindings in the DHCP snooping binding database

show running-config Switch#s

Displays the status of the insertion and removal of the DHCP option 82 field on all interfaces

Dynamic ARP Inspection Dynamic ARP Inspection (DAI) determines the validity of an ARP packet. This feature prevents attacks on the switch by not relaying invalid ARP requests and responses to other ports in the same VLAN. DAI does not work on the 2960.

NOTE: To use this feature, you must have the enhanced multilayer image (EMI) installed on your 3560 switch.

ip arp 3560Switch(config)#i inspection vlan 10

Enables DAI on VLAN 10

ip arp 3560Switch(config)#i inspection vlan 10,20

Enables DAI on VLANs 10 and 20

ip arp 3560Switch(config)#i inspection vlan 10-20

Enables DAI on VLANs 10 to 20 inclusive

ip arp 3560Switch(config)#i inspection validate src-mac

Configures DAI to drop ARP packets when the source MAC address in the body of the ARP packet does not match the source MAC address specified in the Ethernet header. This check is performed on both APR requests and responses.

ip arp 3560Switch(config)#i inspection validate dst-mac

Configures DAI to drop ARP packets when the destination MAC address in the body of the ARP packet does not match the destination MAC address specified in the Ethernet header. This check is performed on both APR requests and responses.

114

802.1x Port-Based Authentication

ip arp 3560Switch(config)#i inspection validate ip

Configures DAI to drop ARP packets that have invalid and unexpected IP addresses in the ARP body, such as 0.0.0.0, 255.255.255.255, or all IP multicast addresses. Sender IP addresses are checked in all ARP requests and responses, and target IP addresses are checked only in ARP responses.

interface Switch(config)#i fastethernet 0/24

Moves to interface config mode

ip arp Switch(config-if)#i inspection trust

Configures the connection between switches as trusted NOTE: By default, all interfaces are untrusted.

Verifying DAI show ip arp inspection Switch#s interfaces

Verifies the dynamic ARP configuration

show ip arp inspection Switch#s vlan 10

Verifies the dynamic ARP configuration for VLAN 10

show ip arp inspection Switch#s statistics vlan 10

Displays the dynamic ARP inspection statistics for VLAN 10

802.1x Port-Based Authentication The IEEE 802.1x standard defines an access control and authentication protocol that prevents unauthorized hosts from connecting to a LAN through publicly accessible ports unless they are properly authenticated. The authentication server authenticates each host connected to a switch port before making available any services offered by the switch or the LAN. aaa new-model Switch(config)#a

Enables authentication, authorization, and accounting (AAA)

aaa authentication Switch(config)#a dot1x default group radius

Creates an 802.1x port-based authentication method list. This method specifies using a RADIUS server for authentication.

802.1x Port-Based Authentication

115

NOTE: A method list describes the sequence and authentication methods to be queried to authenticate a user. The software uses the first method listed to authenticate users; if that method fails to respond, the software selects the next authentication method in the method list. This process continues until there is successful communication with a listed authentication method or until all defined methods are exhausted. If authentication fails at any point in this cycle, the authentication process stops, and no other authentication methods are attempted. NOTE: To create a default list that is used when a named list is not specified, use the default keyword followed by methods that are to be used in default situations. NOTE: When using the aaa authentication dot1x command, you must use at least one of the following keywords: group radius—Use a list of RADIUS servers for authentication. none—Use no authentication. The client is automatically authenticated without the switch using information supplied by the client. This method should only be used as a second method. If the first method of group radius is not successful, the switch will use the second method for authentication until a method is successful. In this case, no authentication would be used. dot1x system-authSwitch(config)#d control

Globally enables 802.1x port-based authentication

interface Switch(config)#i fastethernet 0/1

Moves to interface config mode

dot1x portSwitch(config-if)#d control auto

Enables 802.1x authentication on this interface

116

Cisco Discovery Protocol Security Issues

NOTE: The auto keyword allows the port to begin in the unauthorized state. This will allow only Extensible Authentication Protocol over LAN (EAPOL) frames to be sent and received through the port. Other keywords available here are these: force-authorized—Disables 802.1x authentication and causes the port to transition to the authorized state without any authentication exchange required. This is the default setting. force-unauthorized—Causes the port to remain in the unauthorized state, ignoring all attempts by the client to authenticate. The switch cannot provide authentication services to the client through the interface. show dot1x Switch#s

Verifies your 802.1x entries

Cisco Discovery Protocol Security Issues Although Cisco Discovery Protocol (CDP) is necessary for some management applications, CDP should still be disabled in some instances. Disable CDP globally under these scenarios: • CDP is not required at all. • The device is located in an insecure environment. Use the command no cdp run to disable CDP globally: no cdp run Switch(config)#n

Disable CDP on any interface under these scenarios: • Management is not being performed. • The interface is a nontrunk interface. • The interface is connected to a nontrusted network. Use the interface configuration command no cdp enable to disable CDP on a specific interface: interface fastethernet 0/12 Switch(config)#i no cdp enable Switch(config-if)#n

vty ACLs

117

Configuring the Secure Shell Protocol CAUTION: Secure Shell (SSH) Version 1 implementations have known security issues. It is recommended to use SSH Version 2 whenever possible.

NOTE: To work, SSH requires a local username database, a local IP domain, and an RSA key to be generated. The Cisco implementation of SSH requires Cisco IOS Software to support Rivest, Shamit, Adleman (RSA) authentication and minimum Data Encryption Standard (DES) encryption—a cryptographic software image.

username Roland Switch(config)#u password tower

Creates a locally significant username/ password combination. These are the credentials needed to be entered when connecting to the switch with SSH client software.

ip domain-name Switch(config)#i test.lab

Creates a host domain for the switch

crypto key Switch(config)#c generate rsa

Enables the SSH server for local and remote authentication on the switch and generates an RSA key pair

vty ACLs access-list 10 Switch(config)#a permit host 192.168.1.15

Creates a standard ACL that filters out traffic from source address 192.168.1.15

line vty 0 15 Switch(config)#l

Moves to vty line mode. All commands in this mode will apply to vty lines 0–15 inclusive.

access-class Switch(config-line)#a 10 in

Restricts incoming vty connections to addresses filtered by ACL 10 NOTE: The actual number of vty lines depends on the platform and the version of Cisco IOS Software being run.

118

Disabling Unneeded Services

Restricting Web Interface Sessions with ACLs access-list 10 Switch(config)#a permit host 192.168.1.15

Creates a standard ACL that filters out traffic from source address 192.168.1.15

ip http server Switch(config)#i

Enables the HTTP server on the switch

ip http accessSwitch(config)#i class 10

Applies ACL 10 to the HTTP server

Disabling Unneeded Services TIP: Cisco devices implement various TCP and User Datagram Protocol (UDP) servers to help facilitate management and integration of devices. If these servers are not needed, consider disabling them to reduce security vulnerabilities.

no service tcpSwitch(config)#n small-servers

Disables minor TCP services—echo, discard, chargen, and daytime—available from hosts on the network

no service udpSwitch(config)#n small-servers

Disables minor UDP services—echo, discard, and chargen—available from hosts on the network

no ip finger Switch(config)#n

Disables the finger service. The finger service allows remote users to view the output equivalent to the show users [wide] command. NOTE: The previous version of the [no] ip finger command was the [no] service finger command. The [no] service finger command continues to work to maintain backward compatibility, but support for this command may be removed in some future Cisco IOS release.

no service Switch(config)#n config

Disables the config service. The config service allowed for the autoloading of configuration files from a network server.

no ip http Switch(config)#n server

Disables the HTTP server service

Securing End-Device Access Ports

119

Securing End-Device Access Ports interface range Switch(config)#i fastethernet 0/1 – 24

Enters interface range command mode. All commands entered in this mode will be applied to all interfaces in the range.

switchport Switch(config-if-range)#s host

Enables the switchport host macro

NOTE: The switchport host command is a macro that performs the following actions: • Sets the switch port mode to access • Enables Spanning Tree PortFast • Disables channel grouping The switchport host command does not have a no keyword to disable it. To return an interface to default configuration, use the global configuration command default interface interface-id: default interface fasthethernet 0/1 Switch(config)#d

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CHAPTER 8

Voice Support in Campus Switches This chapter provides information and commands concerning the following topics: • Attaching a Cisco IP Phone • Verifying configuration after attaching a Cisco IP Phone • Configuring AutoQoS: 2960/3560 • Verifying AutoQoS information: 2960/3560 • Configuring AutoQoS: 6500 • Verifying AutoQoS information: 6500

Attaching a Cisco IP Phone mls qos Switch(config)#m

Enables quality of service (QoS) globally on a switch

interface Switch(config)#i fastethernet 0/14

Moves to interface configuration mode

)#switchport Switch(config-if) voice vlan 210

Enables a voice VLAN on the switch port and associates a VLAN ID

mls qos trust Switch(config-if)#m cos

Configures the interface to classify incoming traffic packets according to the class of service (CoS) value. For untagged packets, the default CoS value is used. The default port CoS value is 0.

mls qos trust Switch(config-if)#m dscp

Configures the interface to classify incoming traffic packets according to the differentiated services code point (DSCP) value. For a nonIP packet, the packet CoS value is used if the packet is tagged. For an untagged packet, the default port CoS value is used.

mls qos trust Switch(config-if)#m ip-precedence

Configures the interface to classify incoming packets according to the IP precedence value. For a non-IP packet, the packet CoS value is used if the packet is tagged. For an untagged packet, the default port CoS value is used.

122

Attaching a Cisco IP Phone

mls qos trust Switch(config-if)#m device cisco-phone

Specifies that the Cisco IP Phone is a trusted device

switchport Switch(config-if)#s priority extend cos 5

Sets the priority of data traffic received from the IP Phone access port. The cos value will tell the phone to override the priority received from the PC or attached device with a CoS value of 5. NOTE: The CoS value is from 0 to 7, with 7 being the highest priority. The default value is CoS 0.

switchport Switch(config-if)#s priority extend trust

Sets the priority of data traffic received from the IP Phone access port. The trust argument configures the IP Phone access port to trust the priority received from the PC or attached device.

mls qos trust Switch(config-if)#m extend

Configures the trust mode of the phone NOTE: The mls qos trust extend command is only valid on the 6500 series switch. Although the 6500 series switch is not tested on the BCMSN certification exam, the mls qos trust extend command has been placed in this command guide because of the large number of network professionals working with the 6500 series switch. NOTE: With the mls qos trust extend command enabled, and if you set your phone to trusted mode, all the packets coming from the PC are sent untouched directly through the phone to the 6500 series switch. If you set the phone to untrusted mode, all traffic coming from the PC are re-marked with the configured CoS value before being sent to the 6500 series switch.

Configuring AutoQoS: 2960/3560

123

NOTE: Each time that you enter the mls qos trust extend command, the mode is changed. If the mode was set to trusted, the result of this command would be to change the mode to untrusted. Use the show queueing interface command to display the current trust mode.

Verifying Configuration After Attaching a Cisco IP Phone show interface Switch#s fasthethernet 0/2 switchport

Displays voice parameters configured on the interface

show mls qos interface Switch#s fasthethernet 0/2

Displays QoS parameters configured on the interface

Configuring AutoQoS: 2960/3560 TIP:

QoS is globally enabled when AutoQoS is enabled on the first interface.

interface Switch(config)#i fastethernet 0/12

Moves to interface configuration mode

auto qos voip Switch(config-if)#a cisco-phone

Enables the trusted boundary feature. Cisco Discovery Protocol (CDP) will be used to detect the presence (or absence) of a Cisco IP Phone. TIP: When using the auto qos voip ciscophone command, if a phone is detected, the port is configured to trust the QoS label received in any packet. If a phone is not detected, the port is set not to trust the QoS label.

auto qos voip Switch(config-if)#a trust

Port is configured to trust the CoS label or the DSCP value received on the packet

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Verifying AutoQoS Information: 6500

Verifying AutoQoS Information: 2960/3560 show auto qos Switch#s

Displays initial AutoQoS configuration

show auto qos interface Swithc#s fasthethernet 0/12

Displays initial AutoQoS configuration for the specified port

Configuring AutoQoS: 6500 TIP: Although the 6500 series switch is not tested on the BCMSN certification exam, these commands have been placed in this command guide because of the large number of network professionals working with the 6500 series switch. The 6500 series switch uses the Catalyst operating system as opposed to the Cisco IOS found on the 2960/3560 series.

Console> (enable) set qos autoqos

Applies all global QoS settings to all ports on the switch

Console> (enable) set port qos 3/1 – 48 autoqos trust cos

Applies AutoQoS to ports 3/1–48 and specifies that the ports should trust CoS markings

Console> (enable) set port qos 3/1 – 48 autoqos trust dscp

Applies AutoQoS to ports 3/1–48 and specifies that the ports should trust DSCP markings

Console> (enable) set port qos 4/1 autoqos voip ciscoipphone

Applies AutoQoS settings for any Cisco IP Phone on module 4, port 1

Console> (enable) set port qos 4/1 autoqos voip ciscosoftphone

Applies AutoQoS settings for any Cisco IP SoftPhone on module 4, port 1

Verifying AutoQoS Information: 6500 Console> show port qos

Displays all QoS-related information

Console> show port qos 3/1

Displays all QoS-related information for module 3, port 1

APPENDIX

Create Your Own Journal Here Even though I have tried to be as complete as possible in this reference guide, invariably I will have left something out that you need in your specific day-to-day activities. That is why this section is here. Use these blank lines to enter in your own notes, making this reference guide your own personalized journal.

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